%I A139425
%S A139425 1,1,9,3,3,25,7,21,435,241,3,153,151,493,537,2871,1713,4941,4963,307,
%T A139425 28413,5035,1615,43525,9973
%N A139425 Smallest number k such that M(n)^2-k*M(n)+1 is prime with M(n)= Mersenne 
               primes =A000668(n).
%C A139425 All primes certified using openpfgw_v12 from primeform group
%e A139425 3*3-1*3+1=7 prime 3=M(1)=2^2-1 so k(1)=1
%e A139425 7*7-1*7+1=43 prime 7=M(2)=2^3-1 so k(2)=1
%e A139425 31*31-9*31+1=683 prime 31=M(3)=2^5-1 so k(3)=9
%Y A139425 Cf. A000668, A139424, A139426, A139427, A139428, A139429, A139430, A139421.
%Y A139425 Sequence in context: A037921 A019878 A097902 this_sequence A090485 A021521 
               A011011
%Y A139425 Adjacent sequences: A139422 A139423 A139424 this_sequence A139426 A139427 
               A139428
%K A139425 hard,more,nonn
%O A139425 1,3
%A A139425 Pierre CAMI (pierrecami(AT)tele2.fr), Apr 21 2008