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Challenges

Posts tagged number-theory

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Challenges Find near miss prime multiples.

Given a number $n \geq 3$ as input output the smallest number $k$ such that the modular residues of $k$ by the first $n$ primes is exactly $\{-1,0,1\}$. That is there is a prime in the first $n$ p...

0 answers  ·  posted 8mo ago by WheatWizard‭  ·  edited 8mo ago by WheatWizard‭

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Challenges Determine whether an integer is square-free

An integer is called square-free if it is not a multiple of a perfect square other than 1. For example, 42 is square-free, but 44 is not because it is a multiple of the perfect square 4 = 2². Your...

13 answers  ·  posted 2y ago by celtschk‭  ·  last activity 1y ago by Shaggy‭

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Challenges Are they abundant, deficient or perfect?

Abundant numbers are numbers which are less than their proper divisor sum. For example $18$ is abundant as $1 + 2 + 3 + 6 + 9 = 21 > 18$ Deficient numbers are numbers which are greater than the...

8 answers  ·  posted 2y ago by caird coinheringaahing‭  ·  last activity 2y ago by General Sebast1an‭