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A129310 Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)+1 are twin primes with p(h) = h-th prime. 3

%I #16 Jan 26 2020 11:05:56

%S 4,38,120,122,569,795,1250,1310,1826,3276,3610,4838,4870,4931,4982,

%T 5440,5477,5821,6582,6821,6872,7644,7875,8475,9066,9636,9733,10013,

%U 10960,11171,12079,13887,14338,15669,15952,16040,17597,18921,19525,19694,21321,21372,22750,25998

%N Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)+1 are twin primes with p(h) = h-th prime.

%H Amiram Eldar, <a href="/A129310/b129310.txt">Table of n, a(n) for n = 1..10000</a>

%t PrimePi[Part[#, 1, 1] & /@ FactorInteger /@ Select[Times @@@ Partition[Prime[Range[3*10^4]], 5, 1], PrimeQ[6 # + 1] && PrimeQ[6 # - 1] &]] (* _Amiram Eldar_, Jan 26 2020 after _Giovanni Resta_ at A129311 *)

%o (PARI) isok(k) = isprime(p=6*prime(k)*prime(k+1)*prime(k+2)*prime(k+3)*prime(k+4)-1) && isprime(p+2); \\ _Michel Marcus_, Sep 24 2019

%Y Cf. A129311, A129313.

%K nonn

%O 1,1

%A _Pierre CAMI_, Apr 09 2007

%E More terms from _Michel Marcus_, Sep 24 2019

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Last modified April 19 12:14 EDT 2024. Contains 371792 sequences. (Running on oeis4.)