a(n) = -a(n-1) + 2*a(n-2) + a(n-3), a(0) = -1, a(1) = -2, a(2) = -4.

Terms

a(0) =-1a(1) =-2a(2) =-4a(3) =-1a(4) =-9a(5) =3a(6) =-22a(7) =19a(8) =-60a(9) =76a(10) =-177a(11) =269a(12) =-547a(13) =908a(14) =-1733a(15) =3002a(16) =-5560a(17) =9831a(18) =-17949a(19) =32051a(20) =-58118a(21) =104271a(22) =-188456a(23) =338880a(24) =-611521a(25) =1100825a(26) =-1984987a(27) =3575116a(28) =-6444265a(29) =11609510