A339028 - OEIS

%I #12 Dec 10 2023 17:31:27

%S 1,3,3,9,12,9,28,42,42,28,90,144,162,144,90,297,495,594,594,495,297,

%T 1001,1716,2145,2288,2145,1716,1001,3432,6006,7722,8580,8580,7722,

%U 6006,3432,11934,21216,27846,31824,33150,31824,27846,21216,11934,41990,75582,100776,117572,125970,125970,117572,100776,75582,41990

%N Triangle T(n,m) = 3*(m+1)*C(n+m+3,m)*C(2*n+2,n-m)/((n+m+3)*C(n+1,m)).

%F G.f. ((sqrt(1-4*x*y)-sqrt(1-4*x))/(2*(x-x*y)))^3.

%e 1,

%e 3,3,

%e 9,12,9,

%e 28,42,42,28,

%e 90,144,162,144,

%e 90,297,495,594,594,495,297

%o (Maxima)

%o T(n,m):=if n<m then 0 else (3*(m+1)*(binomial(n+m+3,m))*(binomial(2*n+2,n-m)))/((n+m+3)*(binomial(n+1,m)));

%Y Cf. A000108, A000245, A002057 (row sums), A168256, A120406,

%K nonn,tabl

%O 0,2

%A _Vladimir Kruchinin_, Nov 20 2020