A366273 - OEIS

%I #12 Oct 06 2023 08:33:44

%S 1,1,9,81,849,9681,116601,1459809,18809121,247782369,3322209001,

%T 45187029809,621970864241,8647376531249,121261376439641,

%U 1713085987837889,24358211622230081,348325689458584769,5006342381846708681,72279683684984063249,1047789195353379807121

%N G.f. A(x) satisfies A(x) = 1 + x*(1 + x)^4*A(x)^5.

%F a(n) = Sum_{k=0..n} binomial(4*k,n-k) * binomial(5*k,k)/(4*k+1).

%o (PARI) a(n) = sum(k=0, n, binomial(4*k, n-k)*binomial(5*k, k)/(4*k+1));

%Y Cf. A052709, A366221, A366272.

%Y Cf. A366268.

%K nonn

%O 0,3

%A _Seiichi Manyama_, Oct 06 2023