# Questions tagged [sequence]

For challenges involving sequences, typically of numbers following some pattern.

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### Generalise perfect numbers

Let $\sigma(n)$ represent the divisor sum of $n$ and $\sigma^m(n)$ represent the repeated application of the divisor function $m$ times. Perfect numbers are numbers whose divisor sum equals ...
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### Square root multiples

This code-challenge is based on OEIS sequence A261865. $A261865(n)$ is the least integer $k$ such that some multiple of $\sqrt{k}$ is in the interval $(n,n+1)$. The goal of this challenge is ...
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### Count unrooted, unlabeled binary trees of n nodes

An unrooted binary tree is an unrooted tree (a graph that has single connected component and contains no cycles) where each vertex has exactly one or three neighbors. It is used in bioinformatics to ...
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### Merge Two Paragraphs with Removing Duplicated Lines

Challenge The goal of this challenge is to make a function that takes two paragraphs and output a concatenated result with removing the duplicated overlapped lines due to redundancy (but a single copy ...
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### Linear integer function generator

Inspired by a recent challenge involving Fibonacci numbers in which OEIS was mentioned, I would like to present a challenge of creating a function that generates a wide array of different linear ...
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### Find a sequence in the binary digits of π

Given a binary sequence of finite length, find the starting position where this sequence first appears in the binary digits of π (after the decimal). You can assume that an answer exists for any input ...
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### Squarefree Palindromes [closed]

Create the shortest function, program, or expression that calculates a sequence of squarefree palindromic numbers. A squarefree number is one which is not evenly divisible by a square number (i.e. ...
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### Ken Iverson’s Favourite APL Expression?

Ken Iverson, 1920–2020 Let's implement his favourite expression: Given a row of Pascal's triangle, compute the next row. This can for example be computed by taking the input padded with a zero on the ...
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### The Fibonacci Rectangular Prism Sequence

What is the Fibonacci Rectangular Prism Sequence? The Fibonacci Rectangular Prism Sequence is a sequence derived from the Fibonacci sequence starting with one. The first 3 numbers of the Fibonacci ...
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### Polygons in a cube

Inspired in part by this Mathologer video on gorgeous visual "shrink" proofs, and my general interest in the topic, this challenge will have you count regular polygons with integer ...
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### What valence does this APL train have?

Context In APL, trains are tacit sequences of monadic/dyadic functions that can be called with one or two arguments. We'll code something to check if a given train follows the correct structure we ...
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### The "skip-pure" numbers

The skip-pure numbers are defined with this rule: ...
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### Generate A065825

(This is A065825.) The sequence defaults apply, so you can pick another format other than this one. Given an input integer n, find the smallest number ...
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### How much weight can you lift?

With all the gyms closed down with the COVID-19 situation, we have to exercise with the weight we have lying around at home. The problem is, we have a small selection of plates at varying weights, and ...
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### Donation arms race

The barfoos, a hypothetical alien species, go about charity in an interesting way. Every morning, barfoo Specialists come up with an ordered list of causes to donate to, and for each cause they ...
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### Missile-mounted cameras

You are employed as Administrator in charge of Road Maintenance and Planning. The intelligence division of the Agency for Road Maintenance and Planning has come up with a brilliant and not at all ...
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