cp's OEIS Frontend

A137909 Least k such that k*(2^p-1)*(k*(2^p-1)+1)+1 is prime, where 2^p-1 runs through the Mersenne primes.

%I A137909 #9 Oct 12 2014 11:25:32
%S A137909 1,2,2,3,17,8,3,6,96,9,224,33,260,1044,2397,3,1487,657,9602,2133,
%T A137909 18438,93,17273,32583,66539,9632,1431,100440,150857
%N A137909 Least k such that k*(2^p-1)*(k*(2^p-1)+1)+1 is prime, where 2^p-1 runs through the Mersenne primes.
%e A137909 1*(2^2-1)*(1*(2^2-1)+1)+1=13 prime, 2^2-1 first Mersenne prime, a(1)=1
%e A137909 2*(2^3-1)*(2*(2^3-1)+1)+1=211 prime, 2^3-1 second Mersenne prime, a(2)=2
%Y A137909 Cf. A000043 (Mersenne exponents), A000668 (Mersenne primes).
%Y A137909 Cf. A137906, A137907, A137908.
%K A137909 hard,more,nonn
%O A137909 1,2
%A A137909 _Pierre CAMI_, Feb 22 2008
%E A137909 a(27)-a(29) by _Pierre CAMI_, Oct 11 2014