A366056 - OEIS

%I #8 Sep 27 2023 10:06:42

%S 1,3,15,91,613,4408,33143,257400,2048825,16625940,137033316,

%T 1144010387,9653706723,82208879366,705587243802,6097408839400,

%U 53007770199641,463269048213536,4067950092964440,35871913838983980,317533385082542404,2820492099258807887

%N Expansion of (1/x) * Series_Reversion( x*(1-x)^4/(1-x+x^4) ).

%F a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+1,k) * binomial(4*n-3*k+2,n-4*k).

%o (PARI) a(n) = sum(k=0, n\4, binomial(n+1, k)*binomial(4*n-3*k+2, n-4*k))/(n+1);

%Y Cf. A215341, A366054, A366055.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Sep 27 2023