# Sequences A sequence is a function that maps indexed natural numbers to elements of a set, and may be finite or infinite; sequences are also called arrays, vectors, or lists. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## Chaining Activities -- from text to vectors DevFeed: [Chaining Activities -- from text to vectors]() Original publisher: [Read original article]() Author: Houman Kargaran Published: 2026-08-12T00:00:00Z Content type: tutorial Language: en Sources: [Temporal Blog]() Topics: [data](), [Embeddings](), [on-prem](), [pii](), [Redis](), [retry](), [Sequences]() Tags: [article](), [community](), [data-pipeline](), [embeddings](), [on-prem](), [pii](), [redis](), [retries](), [storage]() ### AI overview This guest post explains a Temporal workflow that chains discrete Activities to process complaints while maintaining a PII boundary. It uses an on-premises all-MiniLM-L6-v2 model for embeddings, caches vectors in Redis, stores them externally, and relies on deterministic workflow sequencing and retry policies. ### Source excerpt Learn how to build a durable, PII-conscious data pipeline with Temporal using on-prem embeddings, idempotent Activities, external vector storage, and retries. ## More whimsical OEIS sequences DevFeed: [More whimsical OEIS sequences]() Original publisher: [Read original article]() Published: 2026-05-22T22:28:34Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences]() Tags: [depths-of-oeis](), [doom](), [oeis](), [sequences](), [shortform](), [xkcd]() ### AI overview An informal survey of whimsical OEIS sequences, including sequences inspired by XKCD, non-reduced fractions, hexadecimal patterns, James Bond primes, random tables, and references to the number 666. ### Source excerpt Here are some more whimsical OEIS sequences I came across. XKCD 2016 joked that "OEIS keeps rejecting my submissions," including one that gives "Integers in increasing order of width when printed in Helvetica." Well, two days after that comic was published (2018-07-09), Hugo Pfoertner published A316600, with a very precise definition. Then he did Arial. Randall Munroe missed a huge opportunity to commit to his bit and actually try to submit some of his sequences before publishing the comic. ## Unusual uses of OEIS sequences on GitHub DevFeed: [Unusual uses of OEIS sequences on GitHub]() Original publisher: [Read original article]() Published: 2026-04-13T14:00:00Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [Open Source](), [GitHub](), [Algorithms]() Tags: [algorithms](), [code](), [coding](), [depths-of-oeis](), [github](), [oeis](), [open-source](), [sequences](), [shortform]() ### AI overview The article surveys unusual uses of OEIS sequences in open-source software on GitHub. It describes their use in the Mercury and Ziffers live-coding music frameworks, the Plato e-reader's pen-size options, and the GC Wizard geocaching app. ### Source excerpt I went hunting for references to the OEIS in open source code, and found some weird ones. There are not one, but two live-coding music frameworks that use OEIS sequences as a source for "anything that can be sequenced" in music. I'm guessing that's used for choosing pseudorandom melodies, interesting rhythyms, or how to overlap tracks in different ways. The first project is called mercury, which is advertised as having "an extensive library of algorithms to generate or transform numbersequences that can modulate parameters. ## The OEIS meta sequence and subway stations DevFeed: [The OEIS meta sequence and subway stations]() Original publisher: [Read original article]() Published: 2026-04-09T13:55:17Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [math](), [Database]() Tags: [database](), [depths-of-oeis](), [new-york-city](), [numberphile](), [oeis](), [quirk](), [sequence](), [sequences](), [shortform](), [train]() ### AI overview This commentary examines OEIS sequence A051070, whose nth term is the nth entry of sequence A_n, or -1 when that sequence lacks enough terms. It highlights unusually large or unknown values, subway-stop sequences included in the OEIS, and self-referential questions involving A051070 and A102288. ### Source excerpt A051070 is a sequence about OEIS sequences. a(n) is the n-th term in sequence A_n (or -1 if A_n doesn't have enough terms). So the first term in A051070 is 1 because A000001 is the number of groups of order n, and that sequence has 1 as its entry in index 1. A000002 is the Kolakoski sequence (what? For another time) and has value 2 in entry 2. The sequence continues: 1, 2, 1, 0, 2, 3, 0, 7, 8, 4, 63, 1, 316, ... ## Waiting for PostgreSQL 19 - Sequence synchronization in logical replication. DevFeed: [Waiting for PostgreSQL 19 - Sequence synchronization in logical replication.]() Original publisher: [Read original article]() Author: depesz Published: 2025-11-11T12:24:23Z Content type: tutorial Language: en Sources: [select \* from depesz;]() Topics: [PostgreSQL](), [Replication](), [Sequences]() Tags: [benchmark](), [logical](), [pg19](), [postgresql](), [psql](), [publications](), [replication](), [sequence](), [sequences](), [synchronization](), [uncategorized](), [upgrade](), [upgrades](), [waiting]() ### AI overview This article demonstrates PostgreSQL 19's planned sequence synchronization for logical replication. It sets up source and destination databases, tests sequence synchronization, finds that resynchronization must be manually invoked, and reports that synchronizing 10,000 sequences took about one second in the author's test. ### Source excerpt First, on 9th of October 2025, Amit Kapila committed patch: Add "ALL SEQUENCES" support to publications. This patch adds support for the ALL SEQUENCES clause in publications, enabling synchronization/replication of all sequences that is useful for upgrades. Publications can now include all sequences via FOR ALL SEQUENCES. psql enhancements: \d shows publications for ... Continue reading "Waiting for PostgreSQL 19 - Sequence synchronization in logical replication." ## Gophercon Latam 2025 - Serving TUIs over SSH using Go ✨ DevFeed: [Gophercon Latam 2025 - Serving TUIs over SSH using Go ✨]() Original publisher: [Read original article]() Author: Carlos Alexandro Becker Published: 2025-05-05T00:00:00Z Content type: article Language: en Sources: [Carlos Becker]() Topics: [ssh](), [Go](), [Text-based user interface](), [Sequences]() Tags: [2025](), [ansi](), [build](), [code](), [event](), [go](), [how-to](), [interviews](), [introduction](), [photos](), [repository](), [sequences](), [serve](), [ssh](), [talk](), [video]() ### AI overview A recap of a Gophercon Latam 2025 talk covering terminal history, ANSI escape sequences, SSH, and how to build and serve a text-based user interface using Bubble Tea and Wish. ### Source excerpt My talk at Gophercon Latam 2025, showing a brief history of terminals, an introduction to ANSI escape sequences, a briefer introduction to SSH, and finally, how to build and serve a TUI using Bubble Tea and Wish. ## Effective Kotlin Item 54: Prefer Sequences for big collections with more than one processing step DevFeed: [Effective Kotlin Item 54: Prefer Sequences for big collections with more than one processing step]() Original publisher: [Read original article]() Published: 2021-09-20T00:00:00Z Content type: tutorial Language: en Sources: [Kt. Academy]() Topics: [Sequences](), [Collections](), [.NET]() Tags: [collections](), [kotlin](), [lazy](), [order-of-operations](), [sequences](), [workshop-learning-programming]() ### AI overview This article explains the difference between Kotlin collection and sequence processing. Sequences are lazy: intermediate operations build a processing chain, and calculations occur during terminal operations. The article discusses their element-by-element ordering, reduced processing work, support for infinite sequences, and avoidance of intermediate collections. ### Source excerpt What the difference between list and sequence processing is, and when each should be preferred. ## pg\_hexedit now supports GiST, GIN, and hash indexes DevFeed: [pg\_hexedit now supports GiST, GIN, and hash indexes]() Original publisher: [Read original article]() Author: Peter Geoghegan (noreply@blogger.com) Published: 2017-12-15T20:29:00Z Content type: release Language: en Sources: [Peter Geoghegan's blog]() Topics: [PostgreSQL](), [hash](), [Sequences]() Tags: [experimental](), [hash](), [index](), [indexes](), [internals](), [nbtree](), [pg-hexedit](), [postgresql](), [sequences]() ### AI overview An update to the experimental pg_hexedit toolkit adds annotations for GiST, GIN, and hash indexes, as well as sequences, when inspecting raw PostgreSQL relation files. The author plans to add BRIN and SP-GiST support later. ### Source excerpt I've added several enhancements to pg_hexedit, the experimental hex editor toolkit that allows you to open up raw PostgreSQL relation files with useful tags and annotations about the state and purpose of each field. The tool now supports annotations for GiST, GIN, and hash indexes, as well as sequences. GIN "posting tree" leaf page. Compressed TIDs are in orange. It wasn't very time consuming to add these enhancements, because most index access methods share the same basic approach to page layout. I plan to add support for the two remaining index access methods (BRIN and SP-GiST) early in the new year. My hope is that this will spur interest in the internals of PostgreSQL index access methods (PDF link), and how they deal with index tuples and space management (PDF link). Hat tip to Pat Shaughnessy, who just today wrote a great blog post on the internals of GiST. The fact that he has done such a thorough job of explaining how GiST works to a wider audience is encouraging. ## English Letter Frequency Counts: Mayzner Revisited or ETAOIN SRHLDCU DevFeed: [English Letter Frequency Counts: Mayzner Revisited or ETAOIN SRHLDCU]() Original publisher: [Read original article]() Published: 2013-01-04T00:00:00Z Content type: article Language: en Sources: [Peter Norvig]() Topics: [data](), [datasets](), [Sequences](), [Google]() Tags: [analysis](), [data](), [google](), [sequences]() ### AI overview This article revisits Mark Mayzner's 1960s study of English letter and letter-sequence frequencies. It analyzes Google Books Ngrams data, with counts organized by word length, letter position, and n-gram length, using a much larger dataset than the original sample. ### Source excerpt An analysis of frequency counts for letters and letter sequences (n-grams), with counts broken out by length of word and poition in word, as well as by length of ngram. A re-implementation of the work done by Mark Mayzner in the 1960s -- but this time with 30 million times more data. ## Reset Counter DevFeed: [Reset Counter]() Original publisher: [Read original article]() Author: Dimitri Fontaine PostgreSQL Major Contributor; Author Published: 2012-10-05T07:44:00Z Content type: tutorial Language: en Sources: [Dimitri Fontaine]() Topics: [PostgreSQL](), [Sequences](), [data]() Tags: [article](), [blog](), [postgresql](), [query](), [sequences](), [window-functions]() ### AI overview A technical walkthrough for calculating the logical value of an ever-increasing counter that periodically resets. It models timestamped measurements and uses PostgreSQL window functions to identify counter wraparounds and retain the relevant values. ### Source excerpt I've been given a nice puzzle that I think is a good blog article opportunity, as it involves some thinking and window functions. ## Complete Sequences and Magic Tricks DevFeed: [Complete Sequences and Magic Tricks]() Original publisher: [Read original article]() Published: 2012-10-02T11:28:16Z Content type: tutorial Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [Algorithm](), [JavaScript](), [Code](), [Programming]() Tags: [algorithm](), [code](), [dynamic-programming](), [greedy-algorithm](), [javascript](), [mathematics](), [numberphile](), [primes](), [programming](), [sequences]() ### AI overview This tutorial explains complete integer sequences through a card trick inspired by a Numberphile video. It presents a greedy algorithm that generates the cards and selects the smallest representation of each number, then shows how to implement the method in JavaScript. ### Source excerpt Numberphile posted a video today describing a neat trick based on complete sequences: The mathematics here is pretty simple, but I noticed at the end of the video that Dr. Grime was constructing the cards by hand, when really this is a job for a computer program. I thought it would be a nice warmup exercise (and a treat to all of the Numberphile viewers) to write a program to construct the cards for any complete sequence. ## Infinitely Many Primes (Using Topology) DevFeed: [Infinitely Many Primes (Using Topology)]() Original publisher: [Read original article]() Published: 2012-09-26T11:51:28Z Content type: tutorial Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [structure]() Tags: [arithmetic](), [numbers](), [primes](), [sequence](), [using]() ### AI overview A proof that there are infinitely many prime numbers using a topology on the integers whose basis consists of two-sided arithmetic progressions. Assuming finitely many primes leads to a finite open complement, contradicting the fact that no finite set is open in this topology. ### Source excerpt Problem: Prove there are infinitely many prime numbers. Solution: First recall that an arithmetic progression with difference $ d$ is a sequence of integers $ a_n \subset \mathbb{Z}$ so that for every pair $ a_k, a_{k+1}$ the difference $ a_{k+1} - a_k = d$. We proceed be defining a topology on the set of integers by defining a basis $ B$ of unbounded (in both directions) arithmetic progressions. That is, an open set in this topology is an arbitrary union of arithmetic progressions from $ -\infty$ to $ \infty$. ## Dynamic Time Warping for Sequence Comparison DevFeed: [Dynamic Time Warping for Sequence Comparison]() Original publisher: [Read original article]() Published: 2012-07-25T20:11:39Z Content type: tutorial Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [Python](), [coding](), [math]() Tags: [dynamic-programming](), [function](), [lambda](), [math](), [mathematics](), [matrix](), [min](), [programming](), [python](), [range](), [return](), [sequences]() ### AI overview This tutorial explains dynamic time warping for comparing sequences of different lengths when their features may occur at different times or rates. It presents a Python implementation using a cost matrix and dynamic programming, with a local numeric distance based on absolute difference. ### Source excerpt Problem: Write a program that compares two sequences of differing lengths for similarity. Solution: (In Python) import math def dynamicTimeWarp(seqA, seqB, d = lambda x,y: abs(x-y)): # create the cost matrix numRows, numCols = len(seqA), len(seqB) cost = [[0 for _ in range(numCols)] for _ in range(numRows)] # initialize the first row and column cost[0][0] = d(seqA[0], seqB[0]) for i in xrange(1, numRows): cost[i][0] = cost[i-1][0] + d(seqA[i], seqB[0]) for j in xrange(1, numCols): cost[0][j] = cost[0][j-1] + d(seqA[0], seqB[j]) # fill in the rest of the matrix for i in xrange(1, numRows): for j in xrange(1, numCols): choices = cost[i-1][j], cost[i][j-1], cost[i-1][j-1] cost[i][j] = min(choices) + d(seqA[i], seqB[j]) for row in cost: for entry in row: print "%03d" % entry, print "" return cost[-1][-1] Discussion: Comparing sequences of numbers can be tricky business. ## Brute-force String Generation in C DevFeed: [Brute-force String Generation in C]() Original publisher: [Read original article]() Published: 2011-08-03T00:00:00Z Content type: tutorial Language: en Sources: [Radek Pazdera]() Topics: [C](), [Sequences](), [Algorithm](), [Code](), [Python]() Tags: [algorithm](), [c](), [implementation](), [language](), [python](), [sequences]() ### AI overview The article presents a C implementation for generating string sequences used in brute-force attacks. It emphasizes speed and efficient generation of input combinations, contrasting the C implementation with earlier Python examples. ### Source excerpt Simple and fast way of generating string sequences in C. ## Finding orphaned sequences DevFeed: [Finding orphaned sequences]() Original publisher: [Read original article]() Author: Dimitri Fontaine PostgreSQL Major Contributor; Author Published: 2010-03-17T12:35:00Z Content type: tutorial Language: en Sources: [Dimitri Fontaine]() Topics: [Sequences](), [Database](), [Query (disambiguation)]() Tags: [database](), [query](), [sequences]() ### AI overview The article presents a query for finding database sequences that are not used as default values in any table columns. ### Source excerpt This time we're having a database where sequences were used, but not systematically as a default value of a given column. It's mainly an historic bad idea, but you know the usual excuse with bad ideas and bad code: the first 6 months it's experimental, after that it's historic. *Not talking about genome orphaned sequences here, though* Still, here's a query for 8.4 that will allow you to list those sequences you have that are not used as a default value in any of your tables: ## Resetting sequences. All of them, please! DevFeed: [Resetting sequences. All of them, please!]() Original publisher: [Read original article]() Author: Dimitri Fontaine PostgreSQL Major Contributor; Author Published: 2010-02-16T15:23:00Z Content type: tutorial Language: en Sources: [Dimitri Fontaine]() Topics: [Sequences](), [Scripting](), [SQL](), [Databases]() Tags: [dump](), [irc](), [production](), [script](), [scripting](), [sequences](), [sql](), [support]() ### AI overview A blog article explains how to restore sequence values after a production dump has been filtered. It describes querying the database catalog for all sequences and generating commands to reset them, with execution in an explicit transaction block. ### Source excerpt So, after restoring a production dump with intermediate filtering, none of our sequences were set to the right value. I could have tried to review the process of filtering the dump here, but it's a one-shot action and you know what that sometimes mean. With some pressure you don't script enough of it and you just crawl more and more. Still, I think how I solved it is worthy of a blog entry. Not that it's about a super unusual clever trick, quite the contrary, because questions involving this trick are often encountered on the support IRC. ## An Exercise in Species Barcoding DevFeed: [An Exercise in Species Barcoding]() Original publisher: [Read original article]() Published: 2009-02-11T00:00:00Z Content type: article Language: en Sources: [Peter Norvig]() Topics: [data](), [Sequences](), [Parsing](), [Programming]() Tags: [algorithm](), [data](), [parsing](), [programming](), [sequences]() ### AI overview An exercise analyzes 1,248 Australian butterfly and moth DNA barcode sequences to examine duplicate and similar sequences. It uses a Python script to compute aggregate statistics and compares Hamming distance with Levenshtein distance for sequences affected by truncation. ### Source excerpt Just in time for Darwin's birthday: an exercise in analyzing the differences in genomes to detect the boundaries between species