a(n) = hypergeom([-n, -n], [1], 1) * n! / (floor(n/2)!)^2.

A295864

a(n) = hypergeom([-n, -n], [1], 1) * n! / (floor(n/2)!)^2.

Terms

    a(0) =1a(1) =2a(2) =12a(3) =120a(4) =420a(5) =7560a(6) =18480a(7) =480480a(8) =900900a(9) =30630600a(10) =46558512a(11) =1955457504a(12) =2498640144a(13) =124932007200a(14) =137680171200

External references