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 A139232 #10 Oct 20 2023 16:54:41
%S A139232 20,72,7968,114816,270336,2146566144,2305843004919250944,
%T A139232 618970015031004121169657856,162258038889176383854312324857856,
%U A139232 170140858942534543324603210697313091584
%N A139232 Second differences of Mersenne primes A000668.
%C A139232 Second differences of even superperfect numbers, multiplied by 2 (see A139236).
%H A139232 G. C. Greubel, <a href="/A139232/b139232.txt">Table of n, a(n) for n = 1..16</a>
%F A139232 a(n) = A139236(n)*2.
%t A139232 A000668 := Select[2^Range[1000] - 1, PrimeQ]; Table[A000668[[n + 2]] - 2*A000668[[n + 1]] + A000668[[n]], {n, 1, 6}] (* _G. C. Greubel_, Oct 03 2017 *)
%t A139232 Differences[2^MersennePrimeExponent[Range[14]]-1,2] (* _Paolo Xausa_, Oct 20 2023 *)
%Y A139232 Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139233, A139234, A139235, A139236, A139237.
%K A139232 nonn
%O A139232 1,1
%A A139232 _Omar E. Pol_, Apr 19 2008
%E A139232 Terms a(7) - a(10) added by _G. C. Greubel_, Oct 03 2017