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 A336980 #18 Apr 29 2021 04:34:44
%S A336980 1,1,2,4,8,13,22,39,65,104,160,263,413,646,975,1479,2198,3354,5017,
%T A336980 7389,10770,15721,22668,32663,47200,67761,96389,135977,191431,268805,
%U A336980 376211,523692,730301,1014029,1401553,1925074,2638522,3608182,4924194,6694070,9088239,12323707,16668255
%N A336980 Expansion of Product_{k>=1} (1 + x^k * (1 + k*x)).
%H A336980 Seiichi Manyama, <a href="/A336980/b336980.txt">Table of n, a(n) for n = 0..1000</a>
%F A336980 G.f.: exp(Sum_{k>=1} x^k * Sum_{d|k} (-1)^(d+1) * (1 + k/d * x)^d / d).
%t A336980 m = 42; CoefficientList[Series[Product[1 + x^k*(1 + k*x), {k, 1, m}], {x, 0, m}], x] (* _Amiram Eldar_, Apr 29 2021 *)
%o A336980 (PARI) N=66; x='x+O('x^N); Vec(prod(k=1, N, 1+x^k*(1+k*x)))
%o A336980 (PARI) N=66; x='x+O('x^N); Vec(exp(sum(k=1, N, x^k*sumdiv(k, d, (-1)^(d+1)*(1+k/d*x)^d/d))))
%Y A336980 Cf. A160571, A336975, A336976, A336977, A336978, A336979.
%K A336980 nonn
%O A336980 0,3
%A A336980 _Seiichi Manyama_, Aug 09 2020