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 A364597 #9 Jul 29 2023 10:56:10 %S A364597 1,1,1,2,5,11,26,71,197,540,1521,4401,12826,37597,111385,332861, %T A364597 1000181,3021071,9174308,27987989,85712801,263438881,812394661, %U A364597 2512807846,7793552386,24233089051,75526196851,235897169106,738271145577,2314825565700,7270693111431 %N A364597 G.f. satisfies A(x) = 1/(1-x) + x^3*(1-x)*A(x)^5. %F A364597 a(n) = Sum_{k=0..floor(n/3)} binomial(n,3*k) * binomial(5*k,k) / (4*k+1). %o A364597 (PARI) a(n) = sum(k=0, n\3, binomial(n, 3*k)*binomial(5*k, k)/(4*k+1)); %Y A364597 Cf. A364595, A364596. %K A364597 nonn,easy %O A364597 0,4 %A A364597 _Seiichi Manyama_, Jul 29 2023