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 A316231 #5 Feb 16 2025 08:33:56 %S A316231 1,-1,0,-2,1,-2,3,-3,6,-8,14,-10,28,-26,41,-73,90,-112,155,-221,288, %T A316231 -501,560,-799,1153,-1610,1953,-3095,4073,-5224,7295,-9536,13536, %U A316231 -18402,24757,-32936,48714,-60790,82101,-113247,153330,-201522,275713,-367041,492991 %N A316231 Expansion of Product_{k>=1} 1/(1 + q(k)*x^k), where q(k) = number of partitions of k into distinct parts (A000009). %H A316231 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PartitionFunctionQ.html">Partition Function Q</a> %H A316231 <a href="/index/Par#part">Index entries for sequences related to partitions</a> %F A316231 G.f.: exp(Sum_{k>=1} Sum_{j>=1} (-1)^k*q(j)^k*x^(j*k)/k). %t A316231 nmax = 44; CoefficientList[Series[Product[1/(1 + PartitionsQ[k] x^k), {k, 1, nmax}], {x, 0, nmax}], x] %t A316231 nmax = 44; CoefficientList[Series[Exp[Sum[Sum[(-1)^k PartitionsQ[j]^k x^(j k)/k, {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x] %t A316231 a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d (-PartitionsQ[d])^(k/d), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 44}] %Y A316231 Cf. A000009, A089254, A270995, A279785, A304786, A316230. %K A316231 sign %O A316231 0,4 %A A316231 _Ilya Gutkovskiy_, Jun 27 2018