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 A381829 #9 Mar 08 2025 09:39:40
%S A381829 1,2,12,97,905,9187,98578,1099980,12636101,148449436,1775331503,
%T A381829 21541303494,264533752068,3281596216087,41062196808517,
%U A381829 517655936768189,6568539787903369,83827401412072474,1075254139150601581,13855040994605807348,179256835556387995412,2327788724156294034612
%N A381829 G.f. A(x) satisfies A(x) = C(x*A(x)) / (1 - x*A(x)^3), where C(x) is the g.f. of A000108.
%F A381829 a(n) = (1/(3*n+1)) * Sum_{k=0..n} binomial(3*n+1,k) * binomial(4*n-3*k,n-k).
%o A381829 (PARI) a(n) = sum(k=0, n, binomial(3*n+1, k)*binomial(4*n-3*k, n-k))/(3*n+1);
%Y A381829 Cf. A188687, A381817, A381828.
%Y A381829 Cf. A000108, A381783.
%K A381829 nonn
%O A381829 0,2
%A A381829 _Seiichi Manyama_, Mar 08 2025