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 A050149 #11 Jul 31 2025 11:54:41
%S A050149 1,15,80,432,2352,12896,71136,394400,2196128,12273648,68811184,
%T A050149 386838480,2179890000,12309739968,69641542848,394643939904,
%U A050149 2239678552640,12727572969680,72415319422992,412470467298032
%N A050149 a(n) = T(n,n-3), array T as in A050143.
%F A050149 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
%F A050149 D-finite with recurrence 3*(n-1)*(n-4)*a(n) +(-23*n^2+139*n-180)*a(n-1) +3*(11*n^2-91*n+170)*a(n-2) -5*(n-2)*(n-7)*a(n-3)=0 for n-3>=4. - _R. J. Mathar_, Jul 31 2025
%K A050149 nonn
%O A050149 3,2
%A A050149 _Clark Kimberling_