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 A351648 #5 Feb 16 2022 11:45:55
%S A351648 1,1,1,6,22,69,224,819,3296,13942,60941,276399,1309207,6479609,
%T A351648 33377271,178186018,983386188,5604262733,32955823822,199771724691,
%U A351648 1246747659198,8000380516898,52728354046939,356593588048023,2472544614851517,17563971319301049,127727505109579581
%N A351648 G.f. A(x) satisfies: A(x) = 1 + x + x^2 * A(x/(1 - x)) / (1 - x)^5.
%F A351648 a(0) = a(1) = 1; a(n) = Sum_{k=0..n-2} binomial(n+2,k+4) * a(k).
%t A351648 nmax = 26; A[_] = 0; Do[A[x_] = 1 + x + x^2 A[x/(1 - x)]/(1 - x)^5 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%t A351648 a[0] = a[1] = 1; a[n_] := a[n] = Sum[Binomial[n + 2, k + 4] a[k], {k, 0, n - 2}]; Table[a[n], {n, 0, 26}]
%Y A351648 Cf. A007476, A045500, A351283, A351437, A351438.
%K A351648 nonn
%O A351648 0,4
%A A351648 _Ilya Gutkovskiy_, Feb 16 2022