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 A381831 #11 Mar 08 2025 09:39:36
%S A381831 1,2,14,133,1456,17306,217066,2827896,37895130,519000037,7232429952,
%T A381831 102220846756,1461817707558,21112968248198,307527937374182,
%U A381831 4512344039147420,66634574697351360,989569163283434676,14769533757869187052,221426909287107012800,3333042591222552282784,50353576994047154278451
%N A381831 Expansion of ( (1/x) * Series_Reversion( x * ((1-x) * (1-x+x^2))^3 ) )^(1/3).
%F A381831 G.f. A(x) satisfies A(x) = C(x*A(x)^2) / (1 - x*A(x)^3), where C(x) is the g.f. of A000108.
%F A381831 a(n) = Sum_{k=0..n} binomial(3*n+k+1,k) * binomial(4*n-2*k,n-k)/(3*n+k+1).
%o A381831 (PARI) my(N=30, x='x+O('x^N)); Vec((serreverse(x*((1-x)*(1-x+x^2))^3)/x)^(1/3))
%Y A381831 Cf. A364592, A381818, A381830.
%Y A381831 Cf. A129442, A381828.
%Y A381831 Cf. A000108.
%K A381831 nonn
%O A381831 0,2
%A A381831 _Seiichi Manyama_, Mar 08 2025