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 A137972 #10 Mar 03 2018 12:28:28
%S A137972 1,1,6,39,320,2787,25788,247731,2449188,24753960,254610962,2656496133,
%T A137972 28046838948,299085697722,3216723340218,34852657892685,
%U A137972 380063012970680,4168108473073596,45941874232280862,508664757809869052
%N A137972 G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^4)^6.
%H A137972 Vaclav Kotesovec, <a href="/A137972/b137972.txt">Table of n, a(n) for n = 0..350</a>
%F A137972 G.f.: A(x) = 1 + x*B(x)^6 where B(x) is the g.f. of A137971.
%F A137972 a(n) = Sum_{k=0..n-1} C(6*(n-k),k)/(n-k) * C(4*k,n-k-1) for n>0 with a(0)=1. - _Paul D. Hanna_, Jun 16 2009
%F A137972 a(n) ~ sqrt(6*s*(1-s)*(4-5*s) / ((184*s - 144)*Pi)) / (n^(3/2) * r^n), where r = 0.0833821738312503523008482260558417829257343369560... and s = 1.287689442730957770948767878255357456556632139740... are real roots of the system of equations s = 1 + r*(1 + r*s^4)^6, 24 * r^2 * s^3 * (1 + r*s^4)^5 = 1. - _Vaclav Kotesovec_, Nov 22 2017
%o A137972 (PARI) {a(n)=local(A=1+x*O(x^n));for(i=0,n,A=1+x*(1+x*A^4)^6);polcoeff(A,n)}
%o A137972 (PARI) a(n)=if(n==0,1,sum(k=0,n-1,binomial(6*(n-k),k)/(n-k)*binomial(4*k,n-k-1))) \\ _Paul D. Hanna_, Jun 16 2009
%Y A137972 Cf. A137971, A137973; A137968, A137970, A137974.
%K A137972 nonn
%O A137972 0,3
%A A137972 _Paul D. Hanna_, Feb 26 2008