Problem 44385. Extra safe primes

Created by Matthew Eicholtz

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Last Solution submitted on Sep 18, 2023

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Mehmet OZC on 16 Oct 2017

15 = 2*7+1 and 7 = 2*3+1 so 15 should be a safe prime. Am I missing something?

Peng Liu on 16 Oct 2017

An (extra) safe prime number itself must be a prime number. Here, 15 is not a prime, so it is not (extra) safe prime

danteliujie on 27 Feb 2019

For case 8, x = 719;
which will lead to 44, not prime, the result should be false, but it's true now.
Am I right?

Matthew Eicholtz on 28 Feb 2019

danteliujie, x = 719 does not lead to 44.

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Problem 44385. Extra safe primes

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Problem 44385. Extra safe primes

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