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 A308338 #5 May 21 2019 02:48:10
%S A308338 1,1,2,9,44,270,2064,17682,171296,1867968,22470840,294493320,
%T A308338 4195969392,64416698112,1059685905264,18609306423120,347179119075840,
%U A308338 6855335163907200,142889687354283264,3133647091691585280,72124075333003155840,1738384773846440146560
%N A308338 Expansion of e.g.f. exp(-1 + Product_{k>=1} (1 + x^k/k)).
%F A308338 a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1)*A007838(k)*a(n-k).
%t A308338 nmax = 21; CoefficientList[Series[Exp[Product[(1 + x^k/k), {k, 1, nmax}] - 1], {x, 0, nmax}], x] Range[0, nmax]!
%Y A308338 Cf. A007838, A308336, A308337.
%K A308338 nonn
%O A308338 0,3
%A A308338 _Ilya Gutkovskiy_, May 20 2019