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 A330017 #4 Nov 27 2019 12:52:47
%S A330017 1,1,3,6,16,21,102,109,565,826,4913,4924,28036,28049,378218,427646,
%T A330017 1841532,1841549,29704312,29704331,182590131,194454702,3660242371,
%U A330017 3660242394,17058569521,17059419626,308650641577,311298706504,1436650115240,1436650115269
%N A330017 a(1) = 1; a(n+1) = Sum_{d|n} binomial(n,d) * a(d).
%t A330017 a[n_] := a[n] = Sum[Binomial[n - 1, d] a[d], {d, Divisors[n - 1]}]; a[1] = 1; Table[a[n], {n, 1, 30}]
%Y A330017 Cf. A003238, A056045.
%K A330017 nonn
%O A330017 1,3
%A A330017 _Ilya Gutkovskiy_, Nov 27 2019