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 A381905 #8 Mar 10 2025 06:57:16
%S A381905 1,2,8,47,331,2570,21204,182383,1617163,14675783,135643839,1272434069,
%T A381905 12083390801,115934171020,1122129142754,10943574296787,
%U A381905 107433077283767,1060800046515405,10528321010319417,104972259713887665,1050936451974803973,10560662821468607719
%N A381905 Expansion of (1/x) * Series_Reversion( x / ((1+x) * B(x)) ), where B(x) is the g.f. of A001764.
%F A381905 G.f. A(x) satisfies A(x) = (1 + x*A(x)) * B(x*A(x)).
%F A381905 a(n) = Sum_{k=0..n} binomial(n+3*k+1,k) * binomial(n+1,n-k)/(n+3*k+1).
%o A381905 (PARI) a(n) = sum(k=0, n, binomial(n+3*k+1, k)*binomial(n+1, n-k)/(n+3*k+1));
%Y A381905 Cf. A381906, A381907.
%Y A381905 Cf. A001764, A381911.
%K A381905 nonn
%O A381905 0,2
%A A381905 _Seiichi Manyama_, Mar 10 2025