This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139237 #14 Oct 20 2023 16:55:10 %S A139237 5,18,1992,28704,67584,536641536,576460751229812736, %T A139237 154742503757751030292414464,40564509722294095963578081214464, %U A139237 42535214735633635831150802674328272896 %N A139237 Second differences of even superperfect numbers A061652, divided by 2. %C A139237 Second differences of Mersenne primes A000668, divided by 4 (see A139232). %C A139237 Also, second differences of superperfect numbers A019279, divided by 2, if there are no odd superperfect numbers. %H A139237 Paolo Xausa, <a href="/A139237/b139237.txt">Table of n, a(n) for n = 1..16</a> %F A139237 a(n) = A139236(n)/2. %t A139237 Differences[2^MersennePrimeExponent[Range[14]]-1,2]/4 (* _Paolo Xausa_, Oct 20 2023 *) %Y A139237 Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139236. %K A139237 nonn %O A139237 1,1 %A A139237 _Omar E. Pol_, Apr 18 2008 %E A139237 More terms from _Michel Marcus_, Jul 09 2017