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 A139236 #16 Mar 05 2020 03:44:38 %S A139236 10,36,3984,57408,135168,1073283072,1152921502459625472, %T A139236 309485007515502060584828928,81129019444588191927156162428928, %U A139236 85070429471267271662301605348656545792 %N A139236 Second differences of even superperfect numbers A061652. %C A139236 Second differences of Mersenne primes A000668, divided by 2 (see A139232). %C A139236 Also, second differences of superperfect numbers A019279, if there are no odd superperfect numbers. %H A139236 Jinyuan Wang, <a href="/A139236/b139236.txt">Table of n, a(n) for n = 1..16</a> %F A139236 a(n) = A139234(n+1) - A139234(n). %t A139236 Differences[2^(Select[Range[512],PrimeQ[2^#-1]&]-1),2] (* _Harvey P. Dale_, Oct 15 2017 *) %Y A139236 Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139237. %K A139236 nonn %O A139236 1,1 %A A139236 _Omar E. Pol_, Apr 18 2008 %E A139236 a(6) corrected and more terms from _Joerg Arndt_, Jul 09 2017