31 questions linked to/from List of primes under a million
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### Shortest test for primality for byte [duplicate]

Write a function which gets as input a number (0 <= n <= 255) stored in 32-bit variable and returns non-zero integer if n ...
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### Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
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### Prime counting function

Introduction The Prime Counting Function, also known as the Pi function $\pi(x)$, returns the amount of primes less than or equal to x. Challenge Your program will take an integer x which you can ...
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### Return the Closest Prime Number

Challenge This is a simple one: Given a positive integer up to 1,000,000, return the closest prime number. If the number itself is prime, then you should return that number; if there are two primes ...
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### Smallest n-digit prime containing only these digits

You will need to generate the smallest prime with n digits, and it will only contain digits specified in the list k. Examples: ...
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### List of first n prime numbers most efficiently and in shortest code [closed]

Rules are simple: First n primes (not primes below n), should be printed to standard output separated by newlines (primes should be generated within the code) primes cannot be generated by an inbuilt ...
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### Looks prime to me!

Figuring out whether a given number is prime, while not very complicated, is kind of hard. But making a guess doesn't need to be. Seeing whether a number is a multiple of 2 or 5 is easy - you can just ...
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### Kolmogorov-mania

The Kolmogorov complexity of a string s is defined as the length of the shortest program P that outputs s. If the length of P is shorter than the length of s, then s is said to be compressible, ...
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### Variable Prime “Twins”

I am 2/3 twins with my brother, i.e. born on the same day of the same month but twelve years later. When I was 5, he was 17, both primes; the last pair of ages we can reasonably count on is [71, 83] ...