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 A366268 #18 Oct 16 2023 04:31:19
%S A366268 1,2,10,90,930,10530,126282,1576410,20268930,266591490,3569991370,
%T A366268 48509238810,667157894050,9269347395490,129908752970890,
%U A366268 1834347364277530,26071297610067970,372683901080814850,5354668071305293450,77286026066830771930
%N A366268 G.f. A(x) satisfies A(x) = 1 + x + x*A(x)^5.
%F A366268 a(n) = Sum_{k=0..n} binomial(4*k+1,n-k) * binomial(5*k,k)/(4*k+1).
%F A366268 a(n) = A366273(n) + A366273(n-1).
%F A366268 G.f.: A(x) = 1/B(-x) where B(x) is the g.f. of A366366.
%o A366268 (PARI) a(n) = sum(k=0, n, binomial(4*k+1, n-k)*binomial(5*k, k)/(4*k+1));
%Y A366268 Cf. A025227, A366266, A366267.
%Y A366268 Cf. A366273, A366366.
%K A366268 nonn
%O A366268 0,2
%A A366268 _Seiichi Manyama_, Oct 06 2023