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 A338814 #20 Apr 28 2021 02:04:02 %S A338814 1,0,4,-6,48,0,1440,-10080,120960,0,7257600,-79833600,958003200,0, %T A338814 348713164800,-3923023104000,41845579776000,0,12804747411456000, %U A338814 -243290200817664000,9731608032706560000,0,2248001455555215360000,-103408066955539906560000 %N A338814 Expansion of e.g.f. log(Product_{k>0} (1 + x^k)^(1/k)). %H A338814 Seiichi Manyama, <a href="/A338814/b338814.txt">Table of n, a(n) for n = 1..450</a> %F A338814 a(n) = (n-1)! * A048272(n). %t A338814 a[n_] := (n - 1)! * DivisorSum[n, (-1)^(# + 1) &]; Array[a, 25] (* _Amiram Eldar_, Apr 28 2021 *) %o A338814 (PARI) N=40; x='x+O('x^N); Vec(serlaplace(log(prod(k=1, N, (1+x^k)^(1/k))))) %o A338814 (PARI) {a(n) = if(n<1, 0, (n-1)!*sumdiv(n, d, (-1)^(d+1)))} %Y A338814 Column 1 of A338813. %Y A338814 Cf. A048272, A168243, A318249. %K A338814 sign %O A338814 1,3 %A A338814 _Seiichi Manyama_, Nov 10 2020