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 A351660 #7 Feb 18 2022 03:04:14
%S A351660 1,1,1,1,3,7,15,33,81,225,679,2139,6931,23185,80809,295141,1128487,
%T A351660 4492363,18506923,78584193,343414489,1544535129,7151822771,
%U A351660 34086446307,167058478355,840700482197,4337529697349,22915761303125,123863743341203,684588061704611,3867278506969535
%N A351660 G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 * A(x/(1 - x)) / (1 - x)^2.
%F A351660 a(0) = a(1) = a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-2,k+1) * a(k).
%t A351660 nmax = 30; A[_] = 0; Do[A[x_] = 1 + x + x^2 + x^3 A[x/(1 - x)]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%t A351660 a[n_] := a[n] = If[n < 3, 1, Sum[Binomial[n - 2, k + 1] a[k], {k, 0, n - 3}]]; Table[a[n], {n, 0, 30}]
%Y A351660 Cf. A040027, A210540, A351437, A351707.
%K A351660 nonn
%O A351660 0,5
%A A351660 _Ilya Gutkovskiy_, Feb 16 2022