A139237 - OEIS

%I #14 Oct 20 2023 16:55:10

%S 5,18,1992,28704,67584,536641536,576460751229812736,

%T 154742503757751030292414464,40564509722294095963578081214464,

%U 42535214735633635831150802674328272896

%N Second differences of even superperfect numbers A061652, divided by 2.

%C Second differences of Mersenne primes A000668, divided by 4 (see A139232).

%C Also, second differences of superperfect numbers A019279, divided by 2, if there are no odd superperfect numbers.

%H Paolo Xausa, <a href="/A139237/b139237.txt">Table of n, a(n) for n = 1..16</a>

%F a(n) = A139236(n)/2.

%t Differences[2^MersennePrimeExponent[Range[14]]-1,2]/4 (* _Paolo Xausa_, Oct 20 2023 *)

%Y Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139236.

%K nonn

%O 1,1

%A _Omar E. Pol_, Apr 18 2008

%E More terms from _Michel Marcus_, Jul 09 2017