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 A346681 #13 Jul 30 2021 10:20:05
%S A346681 1,0,5,30,255,2275,21476,210404,2120041,21830314,228713056,2430255074,
%T A346681 26128088701,283703487059,3106713300821,34270543858459,
%U A346681 380471319687826,4247891403168599,47665096853113576,537244509843680309,6079834137116933061,69054467456964456599
%N A346681 a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(5*k,k) / (4*k + 1).
%H A346681 Seiichi Manyama, <a href="/A346681/b346681.txt">Table of n, a(n) for n = 0..925</a>
%F A346681 G.f. A(x) satisfies: A(x) = 1 / (1 + x) + x * (1 + x)^4 * A(x)^5.
%F A346681 a(n) ~ 5^(5*n + 11/2) / (3381 * sqrt(Pi) * n^(3/2) * 2^(8*n + 7/2)). - _Vaclav Kotesovec_, Jul 30 2021
%t A346681 Table[Sum[(-1)^(n - k) Binomial[5 k, k]/(4 k + 1), {k, 0, n}], {n, 0, 21}]
%t A346681 nmax = 21; A[_] = 0; Do[A[x_] = 1/(1 + x) + x (1 + x)^4 A[x]^5 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%o A346681 (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*binomial(5*k, k)/(4*k + 1)); \\ _Michel Marcus_, Jul 29 2021
%Y A346681 Cf. A002294, A032357, A188678, A345368, A346665.
%Y A346681 Cf. A346680, A346682, A346683, A346684.
%K A346681 nonn
%O A346681 0,3
%A A346681 _Ilya Gutkovskiy_, Jul 29 2021