a(n) = n*(3*n+1)*(n+2)!/24.

A037960

a(n) = n*(3*n+1)*(n+2)!/24.

Terms

    a(0) =0a(1) =1a(2) =14a(3) =150a(4) =1560a(5) =16800a(6) =191520a(7) =2328480a(8) =30240000a(9) =419126400a(10) =6187104000a(11) =97037740800

External references