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 A281266 #23 May 31 2018 03:53:41
%S A281266 1,-1,-1,-1,23,-51,35,-197,1367,-3889,7649,-26258,112739,-350676,
%T A281266 939623,-3063201,11022167,-35276497,106320311,-344831533,1164544273,
%U A281266 -3765456206,11890410454,-38631658591,127610160227,-414671018176,1335126443260,-4348160271568
%N A281266 Main diagonal of A279928.
%H A281266 Vaclav Kotesovec, <a href="/A281266/b281266.txt">Table of n, a(n) for n = 0..1000</a> (terms 0..100 from Seiichi Manyama)
%F A281266 a(n) ~ (-1)^n * c * d^n / sqrt(n), where d = 3.31585574856163070436... and c = 0.20250147602443379616... - _Vaclav Kotesovec_, Apr 17 2017
%F A281266 a(n) = [x^n] exp(n*Sum_{k>=1} (-1)^k*x^k/(k*(1 - x^k)^2)). - _Ilya Gutkovskiy_, May 30 2018
%t A281266 nmax = 30; Table[SeriesCoefficient[Product[1/(1 + x^k)^(m*k), {k, 1, m}], {x, 0, m}], {m, 0, nmax}] (* _Vaclav Kotesovec_, Apr 17 2017 *)
%Y A281266 Cf. A255672, A279928.
%K A281266 sign
%O A281266 0,5
%A A281266 _Seiichi Manyama_, Apr 13 2017