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A023239 Primes p such that 10*p + 7 is also prime. 4

%I #31 Sep 08 2022 08:44:47

%S 3,13,19,31,61,67,79,97,109,127,163,199,223,229,241,277,283,313,367,

%T 379,421,433,439,463,487,523,541,547,571,619,631,673,691,751,757,787,

%U 811,823,829,853,859,883,937,967,1033,1093,1117,1171,1237,1249,1291,1303,1321

%N Primes p such that 10*p + 7 is also prime.

%H John Cerkan, <a href="/A023239/b023239.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) == 1 (mod 6), for n > 1. - _John Cerkan_, Sep 12 2016

%t Select[Prime[Range[200]], PrimeQ[10# + 7] &] (* _Alonso del Arte_, Jun 24 2014 *)

%o (Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(10*n+7)] // _Vincenzo Librandi_, Nov 20 2010

%Y Cf. A023238.

%Y Subsequence of A102342.

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)