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 A171196 #19 Jul 06 2025 10:09:27
%S A171196 1,1,13,397,23261,2532093,520285021,206632208765,161306955003037,
%T A171196 249753449538341821,770275887324912000733,4741871606773351738426877,
%U A171196 58325180751309642789169099037,1434100517517383561901937569640509
%N A171196 G.f. A(x) satisfies A(x) = 1/(1 - x*A(2*x)^6).
%H A171196 Seiichi Manyama, <a href="/A171196/b171196.txt">Table of n, a(n) for n = 0..79</a>
%F A171196 a(n) ~ c * 2^(n*(n+1)/2) * 3^n, where c = 0.363484431362432363073577975298028185297326... - _Vaclav Kotesovec_, Nov 03 2021
%F A171196 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} (1/2)^x_1 * Product_{k=1..7} a(x_k). - _Seiichi Manyama_, Jul 06 2025
%t A171196 nmax = 15; A[_] = 0; Do[A[x_] = 1/(1 - x*A[2*x]^6) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] (* _Vaclav Kotesovec_, Nov 03 2021 *)
%o A171196 (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1/(1-x*subst(A, x, 2*x)^6) ); polcoeff(A, n)}
%Y A171196 Cf. A015083, A171192-A171195, A171197, A171198.
%K A171196 nonn
%O A171196 0,3
%A A171196 _Paul D. Hanna_, Dec 05 2009