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 A364376 #15 Sep 09 2024 09:35:28 %S A364376 1,0,-1,3,-4,-9,73,-212,111,1956,-10078,21466,29823,-418183,1561911, %T A364376 -1722963,-13205004,86962328,-232448945,-109578204,3849218852, %U A364376 -17135183489,27800381006,113891855632,-966644138742,3075070731677,-833503324311,-41673632701038 %N A364376 G.f. satisfies A(x) = (1 + x*A(x)) * (1 - x*A(x)^4). %F A364376 a(n) = Sum_{k=0..n} (-1)^k * binomial(n+3*k+1,k) * binomial(n+3*k+1,n-k) / (n+3*k+1). %F A364376 G.f.: x/series_reversion(x*G(x)), where G(x) = 1 - x^2 + 3*x^3 - 6*x^4 + 6*x^5 + 15*x^6 - ... is the g.f. of A364372. - _Peter Bala_, Aug 27 2024 %o A364376 (PARI) a(n) = sum(k=0, n, (-1)^k*binomial(n+3*k+1, k)*binomial(n+3*k+1, n-k)/(n+3*k+1)); %Y A364376 Cf. A364372, A364374, A364375. %Y A364376 Cf. A215623. %K A364376 sign,easy %O A364376 0,4 %A A364376 _Seiichi Manyama_, Jul 21 2023