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 A318600 #9 Aug 31 2018 03:36:07
%S A318600 1,1,1,4,13,66,394,2759,22053,198481,1984746,21832207,261986098,
%T A318600 3405819275,47681467093,715222006464,11443552081333,194540385382662,
%U A318600 3501726936689833,66532811797106828,1330656235940151698,27943780954743188420,614763181004328313035,14139553163099551199806
%N A318600 a(1) = 1; a(n+1) = Sum_{d|n} (-1)^(n/d+1)*d*a(d).
%H A318600 Robert Israel, <a href="/A318600/b318600.txt">Table of n, a(n) for n = 1..450</a>
%F A318600 L.g.f.: log(Product_{n>=1} (1 + x^n)^a(n)) = Sum_{n>=1} a(n+1)*x^n/n.
%p A318600 f:= proc(n) option remember;
%p A318600 add((-1)^((n-1)/d+1)*d*procname(d), d = numtheory:-divisors(n-1))
%p A318600 end proc:
%p A318600 f(1):= 1:
%p A318600 map(f, [$1..30]); # _Robert Israel_, Aug 30 2018
%t A318600 a[1] = 1; a[n_] := a[n] = Sum[(-1)^((n - 1)/d + 1) d a[d] , {d, Divisors[n - 1]}]; Table[a[n], {n, 24}]
%Y A318600 Cf. A004111, A157311, A318372.
%K A318600 nonn
%O A318600 1,4
%A A318600 _Ilya Gutkovskiy_, Aug 29 2018