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 A371989 #9 Apr 15 2024 09:46:01
%S A371989 1,6,18,-18,-270,486,7938,-17010,-290142,676998,11852082,-29091474,
%T A371989 -518183406,1315388646,23720180130,-61672468338,-1122411776958,
%U A371989 2971089997830,54459919690578,-146181889695762,-2694816626063310,7314502270743270,135469313469987138
%N A371989 G.f. A(x) satisfies A(x) = ( 1 + 9*x*A(x)*(1 + A(x)) )^(1/3).
%F A371989 a(n) = 9^n * Sum_{k=0..n} binomial(n,k) * binomial(n/3+k/3+1/3,n)/(n+k+1).
%o A371989 (PARI) a(n) = 9^n*sum(k=0, n, binomial(n, k)*binomial(n/3+k/3+1/3, n)/(n+k+1));
%Y A371989 Cf. A000302, A371990.
%Y A371989 Cf. A371681.
%K A371989 sign
%O A371989 0,2
%A A371989 _Seiichi Manyama_, Apr 15 2024