a(n) = (n-1)!*(2^n-1) for n>=1, a(0)=0.

Terms

a(0) =0a(1) =1a(2) =3a(3) =14a(4) =90a(5) =744a(6) =7560a(7) =91440a(8) =1285200a(9) =20603520a(10) =371226240a(11) =7428153600a(12) =163459296000