a(n) = a(n-1) - A004001(n)*a(n-2), a(1) = 1, a(2) = 1.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =-3a(4) =0a(5) =12a(6) =12a(7) =-36a(8) =-96a(9) =120a(10) =792a(11) =-48a(12) =-6384a(13) =-6000a(14) =45072a(15) =93072a(16) =-312576a(17) =-1243296a(18) =2195040a(19) =17114592a(20) =-9225888a(21) =-231715584a(22) =-102553152a(23) =3141465024a(24) =4679762304a(25) =-42442213056a(26) =-112638647616a(27) =566436761280