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 A306947 #7 Mar 18 2019 05:50:26
%S A306947 1,1,3,9,48,240,1620,11340,103320,929880,9865800,108523800,1362160800,
%T A306947 17708090400,253361908800,3800428632000,63340477200000,
%U A306947 1076788112400000,19769829743664000,375626765129616000,7640832869429760000,160457490258024960000,3559701523615997760000
%N A306947 Expansion of e.g.f. Product_{k>=0} 1/(1 - x^(2^k)/2^k).
%F A306947 a(n) ~ c * n!, where c = A065446 = 1/A048651 = 1/QPochhammer[1/2] = 3.4627466194550636115379573429244311645407579... - _Vaclav Kotesovec_, Mar 18 2019
%t A306947 nmax = 22; CoefficientList[Series[Product[1/(1 - x^2^k/2^k), {k, 0, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
%t A306947 nmax = 22; CoefficientList[Series[Exp[Sum[Sum[Boole[IntegerQ[Log[2, d]]] d^(1 - k/d), {d, Divisors[k]}] x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
%t A306947 a[n_] := a[n] = If[n == 0, 1, (n - 1)! Sum[Sum[Boole[IntegerQ[Log[2, d]]] d^(1 - k/d), {d, Divisors[k]}] a[n - k]/(n - k)!, {k, 1, n}]]; Table[a[n], {n, 0, 22}]
%Y A306947 Cf. A007841, A319105.
%K A306947 nonn
%O A306947 0,3
%A A306947 _Ilya Gutkovskiy_, Mar 17 2019