%I A139257
%S A139257 6,14,62,254,16382,262142,4294967294
%N A139257 Twice Mersenne primes A000668(n).
%F A139257 a(n) = 2*A000668(n).
%Y A139257 Cf. A000668, A139256.
%Y A139257 Sequence in context: A118432 A032404 A059954 this_sequence A056842 A130263 
               A077401
%Y A139257 Adjacent sequences: A139254 A139255 A139256 this_sequence A139258 A139259 
               A139260
%K A139257 nonn
%O A139257 1,1
%A A139257 Omar E. Pol (info(AT)polprimos.com), Apr 23 2008