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 A243408 Primes p such that 10p-1, 10p-3, 10p-7 and 10p-9 are all prime. 0

%I #19 Mar 15 2015 18:19:42

%S 2,11,83,149,347,1301,1607,2531,6299,7727,8273,17117,20183,21737,

%T 24371,26669,39227,40277,53951,54917,63347,66359,66467,73637,82217,

%U 82373,101537,102251,106397,106871,117203,132971,134033,135221,140237,144701,146141,151433,152597

%N Primes p such that 10p-1, 10p-3, 10p-7 and 10p-9 are all prime.

%C This is a subsequence of A064975.

%e 2 is prime, 10*2-1 = 19 is prime, 10*2-3 = 17 is prime, 10*2-7 = 13 is prime, 10*2-9 = 11 is prime. Thus 2 is a member of this sequence.

%t Select[ Range@ 153000],PrimeQ[#] && PrimeQ[10#-1] && PrimeQ[10#-3] && PrimeQ[10#-7] && PrimeQ[10#-9] &] (* _Robert G. Wilson v_, Jun 06 2014 *)

%o (Python)

%o import sympy

%o from sympy import isprime

%o from sympy import prime

%o {print(prime(n),end=', ') for n in range(1,10**5) if isprime(10*prime(n)-1) and isprime(10*prime(n)-3) and isprime(10*prime(n)-7) and isprime(10*prime(n)-9)}

%o (PARI) for(n=1,10^5,if(ispseudoprime(10*prime(n)-1) && ispseudoprime(10*prime(n)-3) && ispseudoprime(10*prime(n)-7) && ispseudoprime(10*prime(n)-9),print1(prime(n),", ")))

%Y Cf. A067267, A064975.

%K nonn

%O 1,1

%A _Derek Orr_, Jun 04 2014

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Last modified July 25 05:51 EDT 2024. Contains 374586 sequences. (Running on oeis4.)