A050149 - OEIS

%I #9 Feb 14 2021 02:20:38

%S 1,15,80,432,2352,12896,71136,394400,2196128,12273648,68811184,

%T 386838480,2179890000,12309739968,69641542848,394643939904,

%U 2239678552640,12727572969680,72415319422992,412470467298032

%N a(n) = T(n,n-3), array T as in A050143.

%F a(n) = Sum_{s=1..n} binomial(n,s)*binomial(s+n-5,n-4) = n*hypergeom([-n + 1, n-3], [2], -1) for n >= 4 and a(1) = 1. - _Petros Hadjicostas_, Feb 14 2021

%K nonn

%O 3,2

%A _Clark Kimberling_