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 A371368 #11 Mar 20 2024 09:39:44
%S A371368 1,8,127,2514,55679,1320530,32800020,842314362,22182639823,
%T A371368 595816941756,16259068712391,449504473152288,12563255467347012,
%U A371368 354392729335581224,10076681024065204760,288500953324319325402,8310071739586606559151
%N A371368 Expansion of (1/x) * Series_Reversion( x * (1-7*x)^2 / (1-6*x) ).
%H A371368 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A371368 a(n) = (1/(n+1)) * Sum_{k=0..n} 6^(n-k) * binomial(2*n+k+1,k) * binomial(2*n,n-k).
%o A371368 (PARI) my(N=20, x='x+O('x^N)); Vec(serreverse(x*(1-7*x)^2/(1-6*x))/x)
%o A371368 (PARI) a(n) = sum(k=0, n, 6^(n-k)*binomial(2*n+k+1, k)*binomial(2*n, n-k))/(n+1);
%Y A371368 Cf. A081178.
%K A371368 nonn
%O A371368 0,2
%A A371368 _Seiichi Manyama_, Mar 19 2024