a(n) = a(n-2) - (n-1)*a(n-3), with a(0) = 0, a(1) = 1, a(2) = 2.

Terms

a(0) =0a(1) =1a(2) =2a(3) =1a(4) =-1a(5) =-7a(6) =-6a(7) =-1a(8) =43a(9) =47a(10) =52a(11) =-383a(12) =-465a(13) =-1007a(14) =4514a(15) =5503a(16) =19619a(17) =-66721a(18) =-73932a(19) =-419863a(20) =1193767a(21) =1058777a(22) =10010890a(23) =-25204097a(24) =-14340981a(25) =-265465457a(26) =615761444a(27) =107400049a(28) =7783328783a(29) =-17133920383