cp's OEIS Frontend

A137907 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 A137907 #12 Sep 23 2019 13:33:07
%S A137907 1,1,9,6,9,24,4,7,28,70,73,121,511,106,343,2169,1423,2146,5736,4444,
%T A137907 2484,2310,2679,25623,2481,39213
%N A137907 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 A137907 1*(2^2-1)*(1*(2^2-1)-1)+1=7 prime, 2^2-1 first Mersenne prime, a(1)=1;
%e A137907 1*(2^3-1)*(1*(2^3-1)-1)+1=43 prime, 2^3-1 second Mersenne prime, a(2)=1.
%Y A137907 Cf. A137906, A137908, A137909.
%K A137907 nonn,hard,more
%O A137907 1,3
%A A137907 _Pierre CAMI_, Feb 22 2008
%E A137907 Corrected by _Pierre CAMI_, Jun 16 2012