Problem 44385. Extra safe primes

• Created by Matthew Eicholtz
• Appears in 3 groups

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By solving this problem, you will make progress in the following group(s)

Cody5:Easy

• 31 Problems
• 159 Finishers

Number theory

• 44 Problems
• 21 Finishers

The Prime Directive

• 14 Problems
• 37 Finishers

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Did you know that the number 5 is the first safe prime? A safe prime is a prime number that can be expressed as 2p+1, where p is also a prime.

To celebrate Cody's Five-Year Anniversary, write a function to determine if a positive integer n is a safe prime in which the prime p (such that n=2p+1) is also a safe prime.

Examples

isextrasafe(5) = false % because 5=2*2+1 and 2 is not a safe prime
isextrasafe(23) = true % because 23=2*11+1 and 11 is also a safe prime (11=2*5+1)

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Solution Stats

22.45% Correct | 77.55% Incorrect

• 4690 Solutions
• 741 Solvers

Last Solution submitted on Mar 05, 2025

Last 200 Solutions

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