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

Terms

a(0) =0a(1) =1a(2) =-1a(3) =-1a(4) =3a(5) =-1a(6) =-5a(7) =7a(8) =3a(9) =-17a(10) =11a(11) =23a(12) =-45a(13) =-1a(14) =91a(15) =-89a(16) =-93a(17) =271a(18) =-85a(19) =-457a(20) =627a(21) =287a(22) =-1541a(23) =967a(24) =2115a(25) =-4049a(26) =-181a(27) =8279a(28) =-7917a(29) =-8641