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 A366053 #8 Sep 27 2023 10:06:47
%S A366053 1,3,15,92,628,4579,34917,275041,2220472,18275896,152780718,
%T A366053 1293657534,11072033677,95629771059,832460471465,7296161486583,
%U A366053 64331378963164,570228657335744,5078345448484216,45418278349485960,407749837317844851,3673300856466182388
%N A366053 Expansion of (1/x) * Series_Reversion( x*(1-x)^4/(1-x+x^3) ).
%F A366053 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(n+1,k) * binomial(4*n-2*k+2,n-3*k).
%o A366053 (PARI) a(n) = sum(k=0, n\3, binomial(n+1, k)*binomial(4*n-2*k+2, n-3*k))/(n+1);
%Y A366053 Cf. A049128, A114997, A366051, A366052.
%K A366053 nonn
%O A366053 0,2
%A A366053 _Seiichi Manyama_, Sep 27 2023