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 A344735 #11 Jun 07 2021 14:55:27
%S A344735 1,4,24,156,1120,8740,73384,657900,6259184,62876852,664134968,
%T A344735 7349666684,84956020864,1023006054980,12802727760840,166174971580684,
%U A344735 2232866214809360,31007771007956948,444360490882720344,6562410784684023452,99749853821538893216,1558780425524233360740
%N A344735 a(0) = 1; a(n) = 4 * Sum_{k=1..n} binomial(n,k) * a(k-1).
%F A344735 G.f. A(x) satisfies: A(x) = 1 + 4 * x * A(x/(1 - x)) / (1 - x)^2.
%t A344735 a[0] = 1; a[n_] := a[n] = 4 Sum[Binomial[n, k] a[k - 1], {k, 1, n}]; Table[a[n], {n, 0, 21}]
%t A344735 nmax = 21; A[_] = 0; Do[A[x_] = 1 + 4 x A[x/(1 - x)]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%Y A344735 Cf. A040027, A078944, A078945, A094417, A343523, A343975, A344840, A345077, A345078, A345081.
%K A344735 nonn
%O A344735 0,2
%A A344735 _Ilya Gutkovskiy_, Jun 07 2021