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

Terms

a(0) =0a(1) =1a(2) =-3a(3) =3a(4) =-1a(5) =-5a(6) =11a(7) =-13a(8) =3a(9) =19a(10) =-45a(11) =51a(12) =-13a(13) =-77a(14) =179a(15) =-205a(16) =51a(17) =307a(18) =-717a(19) =819a(20) =-205a(21) =-1229a(22) =2867a(23) =-3277a(24) =819a(25) =4915a(26) =-11469a(27) =13107a(28) =-3277a(29) =-19661