a(n) = (Sum_{k=0..n-1} C(n-1,k)^2*C(-n-1,k)^2/C(k+2,2))/n.

A246875

a(n) = (Sum_{k=0..n-1} C(n-1,k)^2*C(-n-1,k)^2/C(k+2,2))/n.

Terms

    a(0) =1a(1) =2a(2) =13a(3) =134a(4) =1783a(5) =27950a(6) =491335a(7) =9401390a(8) =192033565a(9) =4131488426a(10) =92723165533

External references