a(n) = ((1+n)*floor(1+n/2))*(n!/floor(1+n/2)!)^2.

A329965

a(n) = ((1+n)*floor(1+n/2))*(n!/floor(1+n/2)!)^2.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =72a(4) =240a(5) =7200a(6) =25200a(7) =1411200a(8) =5080320a(9) =457228800a(10) =1676505600a(11) =221298739200a(12) =821966745600

External references