a(n) = -(n-3)*a(n-1) + 2*(n-2)^2.

Terms

a(0) =2a(1) =6a(2) =6a(3) =14a(4) =-6a(5) =102a(6) =-514a(7) =3726a(8) =-29646a(9) =267014a(10) =-2669898a(11) =29369166a(12) =-352429654a(13) =4581585894a(14) =-64142202066a(15) =962133031502