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 A369509 #9 Jan 25 2024 07:50:25
%S A369509 1,6,61,756,10406,152880,2348164,37250298,605592377,10036783746,
%T A369509 168947499695,2880456168330,49638925087101,863251245610368,
%U A369509 15130529347412496,267011151724625220,4740245924729076390,84599747038748783220,1516992745930706932654
%N A369509 Expansion of (1/x) * Series_Reversion( x * ((1-x)^2-x)^2 ).
%H A369509 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369509 a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(2*n+k+1,k) * binomial(5*n+k+3,n-k).
%o A369509 (PARI) my(N=20, x='x+O('x^N)); Vec(serreverse(x*((1-x)^2-x)^2)/x)
%o A369509 (PARI) a(n) = sum(k=0, n, binomial(2*n+k+1, k)*binomial(5*n+k+3, n-k))/(n+1);
%Y A369509 Cf. A369510, A369511.
%K A369509 nonn
%O A369509 0,2
%A A369509 _Seiichi Manyama_, Jan 25 2024