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 A171208 #18 Jul 08 2025 07:46:36
%S A171208 1,1,14,476,31640,3953488,939383200,433281169216,393718899904640,
%T A171208 710399428248892928,2554705943898166145024,18342976469146094416494592,
%U A171208 263185684727811758287894478848,7549222852919288301041224694890496,432993292623369448352459156263293419520
%N A171208 G.f. A(x) satisfies A(x) = 1 + x*A(2*x)^7.
%H A171208 Seiichi Manyama, <a href="/A171208/b171208.txt">Table of n, a(n) for n = 0..79</a>
%F A171208 a(0) = 1; a(n) = 2^(n-1) * Sum_{x_1, x_2, ..., x_7>=0 and x_1+x_2+...+x_7=n-1} Product_{k=1..7} a(x_k). - _Seiichi Manyama_, Jul 08 2025
%t A171208 terms = 15; A[_] = 0; Do[A[x_] = 1+x*A[2x]^7 + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* _Stefano Spezia_, Apr 02 2025 *)
%o A171208 (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A, x, 2*x)^7); polcoeff(A, n)}
%Y A171208 Cf. A135867, A171200-A171207, A171209, A171210-A171211, A343439.
%Y A171208 Cf. A171196.
%K A171208 nonn
%O A171208 0,3
%A A171208 _Paul D. Hanna_, Dec 05 2009