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 A261998 #17 Jul 05 2016 05:21:19
%S A261998 1,3,5,10,17,26,43,65,95,140,201,283,395,545,740,1002,1343,1780,2350,
%T A261998 3077,4002,5183,6670,8535,10880,13801,17426,21925,27475,34297,42677,
%U A261998 52926,65415,80625,99077,121403,148386,180890,219960,266857,323002,390086,470125
%N A261998 Expansion of Product_{k>=1} (1-x^k)*(1+x^k)^4.
%C A261998 In general, if m > 2 and g.f. = Product_{k>=1} (1-x^k)*(1+x^k)^m, then a(n) ~ exp(Pi*sqrt((m-2)*n/3)) / (2^((m+1)/2) * sqrt(n)).
%C A261998 Equals A000009 convolved with A085140. - _George Beck_, Jul 03 2016
%H A261998 Vaclav Kotesovec, <a href="http://arxiv.org/abs/1509.08708">A method of finding the asymptotics of q-series based on the convolution of generating functions</a>, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 16.
%F A261998 a(n) ~ exp(sqrt(2*n/3)*Pi) / (2^(5/2) * sqrt(n)).
%t A261998 nmax = 80; CoefficientList[Series[Product[(1 - x^k) * (1 + x^k)^4, {k, 1, nmax}], {x, 0, nmax}], x]
%Y A261998 Cf. A085140, A262380.
%K A261998 nonn
%O A261998 0,2
%A A261998 _Vaclav Kotesovec_, Sep 08 2015