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 A321384 #11 Nov 13 2018 08:37:14 %S A321384 1,-1,1,-4,17,-86,514,-3599,28809,-259285,2592766,-28520427,342245654, %T A321384 -4449193503,62288705445,-934330581764,14949289337033, %U A321384 -254137918729562,4574482536873349,-86915168200593632,1738303364014465422,-36504370644303777464,803096154174654583783,-18471211546017055427010 %N A321384 a(1) = 1; a(n+1) = -Sum_{d|n} d*a(d). %H A321384 Seiichi Manyama, <a href="/A321384/b321384.txt">Table of n, a(n) for n = 1..450</a> %F A321384 L.g.f.: log(Product_{n>=1} (1 - x^n)^a(n)) = Sum_{n>=1} a(n+1)*x^n/n. %F A321384 a(n) ~ -(-1)^n * c * (n-1)!, where c = 0.7144978951771230847588633755835851845867260778566988217176856019246992... - _Vaclav Kotesovec_, Nov 09 2018 %t A321384 a[1] = 1; a[n_] := a[n] = -Sum[d a[d], {d, Divisors[n - 1]}]; Table[a[n], {n, 24}] %o A321384 (PARI) a(n) = if (n==1, 1, -sumdiv(n-1, d, d*a(d))); \\ _Michel Marcus_, Nov 09 2018 %Y A321384 Cf. A281487, A318372. %K A321384 sign %O A321384 1,4 %A A321384 _Ilya Gutkovskiy_, Nov 08 2018