cp's OEIS Frontend

A137906 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 A137906 #7 Sep 23 2019 13:32:52
%S A137906 1,1,1,1,1,4,1,27,14,34,6,132,97,1,500,1816,1292,136,2445,15,1934,
%T A137906 5472,1584,2734,21022,5870
%N A137906 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 A137906 1*(2^2-1)*(1*(2^2-1)-1)-1=5 prime, 2^2-1 first Mersenne prime, a(1)=1;
%e A137906 1*(2^3-1)*(1*(2^3-1)-1)-1=41 prime, 2^3-1 second Mersenne prime, a(2)=1.
%Y A137906 Cf. A137907, A137908, A137909.
%K A137906 nonn,hard,more
%O A137906 1,6
%A A137906 _Pierre CAMI_, Feb 22 2008