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A120364 Primes p such that p^2-p-1 and p^2-p+1 are twin primes. 5

%I #23 Jul 25 2021 11:55:27

%S 3,7,67,139,379,457,1201,1381,1549,1567,1747,1789,2137,2557,2647,2731,

%T 4057,4159,4447,4561,5179,5641,6397,9157,9661,9829,9967,10369,11467,

%U 11677,12487,12781,13339,13399,15241,17299,17977,19207,19417,19429

%N Primes p such that p^2-p-1 and p^2-p+1 are twin primes.

%C One more than the entries of (A006093 intersect A088485). - _Danny Rorabaugh_, May 15 2017

%H Pierre CAMI, <a href="/A120364/b120364.txt">Table of n, a(n) for n = 1..10000</a>

%e 3*3-3-1=5 3*3-3+1=7, 5 and 7 twin primes so a(1)=3;

%e 5*5-5-1=19 5*5-5+1=21 composite;

%e 7*7-7-1=41 7*7-7+1=43, 41 and 43 twin primes so a(2)=7.

%t Select[Prime[Range[2500]], PrimeQ[ #^2 - # - 1] && PrimeQ[ #^2 - # + 1] &] (* _Stefan Steinerberger_, Jul 22 2006 *)

%t Select[Prime[Range[2500]],AllTrue[#^2-#+{1,-1},PrimeQ]&] (* _Harvey P. Dale_, Jul 25 2021 *)

%Y Cf. A088483, A088485.

%K nonn

%O 1,1

%A _Pierre CAMI_, Jun 26 2006

%E More terms from _Stefan Steinerberger_ and _Rick L. Shepherd_, Jul 22 2006

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)