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 A139234 #14 Aug 18 2020 14:27:41
%S A139234 2,12,48,4032,61440,196608,1073479680,1152921503533105152,
%T A139234 309485008668423564117934080,81129328929596860350720280363008,
%U A139234 85070510600596201259161956068936908800
%N A139234 First differences of even superperfect numbers A061652.
%C A139234 First differences of Mersenne primes A000668, divided by 2 (see A139231).
%C A139234 Also, first differences of superperfect numbers A019279, if there are no odd superperfect numbers.
%F A139234 a(n) = A061652(n+1) - A061652(n) = A139231(n)/2. Also, a(n) = A019279(n+1) - A019279(n), if there are no odd superperfect numbers.
%e A139234 a(2) = 12 because A061652(2) = 4 and A061652(3) = 16 then 16 - 4 = 12.
%t A139234 Differences[Table[2^(MersennePrimeExponent[n]-1),{n,12}]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 18 2020 *)
%Y A139234 Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139235, A139236, A139237.
%K A139234 nonn
%O A139234 1,1
%A A139234 _Omar E. Pol_, Apr 18 2008
%E A139234 a(8)-a(11) from A139231(n)/2 by _Jinyuan Wang_, Mar 04 2020