766192176domain: NAppears in sequencesa(n) = binomial(n+4,4)*binomial(n+5,4)*binomial(n+6,4)/75.at n=14A107915Let df(n,k) = Product_{i=0..k-1} (n-i) be the descending factorial and let P(m,n) = df(n-1,m-1)^2*(2*n-m)/((m-1)!*m!). Sequence gives P(6,n).at n=19A132464