a(n) = a(n-1) - (n-1)(n-2)a(n-2).

Terms

a(0) =1a(1) =1a(2) =1a(3) =-1a(4) =-7a(5) =5a(6) =145a(7) =-5a(8) =-6095a(9) =-5815a(10) =433025a(11) =956375a(12) =-46676375a(13) =-172917875a(14) =7108596625a(15) =38579649875