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 A120975 #11 Mar 01 2025 08:35:46
%S A120975 1,1,8,108,1888,38798,894308,22517256,609112756,17507219813,
%T A120975 530495478900,16850219461706,558608940038072,19263089278722726,
%U A120975 689119527976265884,25519081467271687938,976447764170903902364
%N A120975 G.f. A(x) satisfies A(x) = 1 + x*A(x)^4 * A(x*A(x)^4)^4.
%F A120975 G.f. A(x) satisfies: A(x) = G(G(x)-1), A(G(x)-1) = G(A(x)-1), A(x) = G(x*A(x)^4) and A(x/G(x)^4) = G(x), where G(x) is the g.f. of A120974 and satisfies G(x/G(x)^4) = 1 + x.
%F A120975 From _Seiichi Manyama_, Mar 01 2025: (Start)
%F A120975 Let a(n,k) = [x^n] A(x)^k.
%F A120975 a(n,0) = 0^n; a(n,k) = k * Sum_{j=0..n} binomial(4*n+k,j)/(4*n+k) * a(n-j,4*j). (End)
%o A120975 (PARI) {a(n)=local(A,G=[1,1]);for(i=1,n,G=concat(G,0); G[ #G]=-Vec(subst(Ser(G),x,x/Ser(G)^4))[ #G]); A=Vec(((Ser(G)-1)/x)^(1/4));A[n+1]}
%o A120975 (PARI) a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(4*n+k, j)/(4*n+k)*a(n-j, 4*j))); \\ _Seiichi Manyama_, Mar 01 2025
%Y A120975 Cf. A120974; variants: A110447, A120971, A120973, A120977.
%K A120975 nonn
%O A120975 0,3
%A A120975 _Paul D. Hanna_, Jul 20 2006