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A098917 Least k such that k*Mersenne-prime(n)*Mersenne-prime(n+1) + 1 is prime. 0

%I

%S 2,6,4,16,36,6,42,24,172,18,52,54,6,130

%N Least k such that k*Mersenne-prime(n)*Mersenne-prime(n+1) + 1 is prime.

%e 2*(2^2-1)*(2^3-1) + 1 = 43 prime so k(1)=2

%e 2*(2^3-1)*(2^5-1) + 1 = 435 composite

%e 4*(2^3-1)*(2^5-1) + 1 = 867 composite

%e 6*(2^3-1)*(2^5-1) + 1 = 1303 prime so k(2)=6

%K nonn

%O 1,1

%A _Pierre CAMI_, Oct 17 2004

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Last modified January 20 22:57 EST 2020. Contains 331104 sequences. (Running on oeis4.)