A transform of C(n,2).

Terms

a(0) =0a(1) =0a(2) =1a(3) =9a(4) =60a(5) =360a(6) =2040a(7) =11088a(8) =58240a(9) =297216a(10) =1480320a(11) =7223040a(12) =34636800a(13) =163657728a(14) =763549696a(15) =3523645440a(16) =16107110400a(17) =73016672256a(18) =328570011648