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 A281683 #22 May 11 2018 09:59:15
%S A281683 1,-1,2,-5,10,-18,32,-59,106,-181,305,-518,867,-1418,2301,-3724,5966,
%T A281683 -9448,14862,-23263,36165,-55802,85609,-130732,198574,-299941,450946,
%U A281683 -675153,1006395,-1493598,2207928,-3251926,4771934,-6977018,10166502,-14766512,21379861
%N A281683 Expansion of Product_{k>=1} (1 - x^(2*k-1))^(2*k-1)/(1 - x^(2*k))^(2*k).
%H A281683 Seiichi Manyama, <a href="/A281683/b281683.txt">Table of n, a(n) for n = 0..10000</a>
%F A281683 a(n) = (-1)^n * A224364(n).
%F A281683 a(n) ~ (-1)^n * exp(1/6 + 3 * 2^(-5/3) * (7*Zeta(3))^(1/3) * n^(2/3)) * (7*Zeta(3))^(2/9) / (2^(25/36) * A^2 * sqrt(3*Pi) * n^(13/18)), where A is the Glaisher-Kinkelin constant A074962. - _Vaclav Kotesovec_, Nov 09 2017
%t A281683 nmax = 50; CoefficientList[Series[Product[(1 - x^k)^k/(1 - x^(2*k))^(4*k), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Nov 09 2017 *)
%t A281683 nmax = 50; CoefficientList[Series[Product[1/((1 + x^k)^(4*k)*(1 - x^k)^(3*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Nov 09 2017 *)
%Y A281683 Cf. A224364, A285069, A281781.
%K A281683 sign
%O A281683 0,3
%A A281683 _Seiichi Manyama_, Apr 14 2017