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A134304 Least k such that k*2^n*(k*2^n-1)-1 and k*2^n*(k*2^n-1)+1 are twin primes. 2

%I #6 Sep 17 2019 10:31:51

%S 2,1,2,1,11,21,57,211,141,156,78,39,140,70,35,214,107,90,45,309,330,

%T 165,120,60,30,15,435,651,420,210,105,429,1143,576,288,144,72,36,18,9,

%U 116,58,29,2286,1143,1638,819,1071,983,1983

%N Least k such that k*2^n*(k*2^n-1)-1 and k*2^n*(k*2^n-1)+1 are twin primes.

%o (PARI) a(n) = {my(k=1); while (!(isprime(p=k*2^n*(k*2^n-1)-1) && isprime(p+2)), k++); k;} \\ _Michel Marcus_, Sep 17 2019

%Y Cf. A134303, A134305.

%K nonn

%O 1,1

%A _Pierre CAMI_, Oct 19 2007

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)