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

Terms

a(0) =1a(1) =-2a(2) =4a(3) =-4a(4) =0a(5) =16a(6) =-48a(7) =96a(8) =-128a(9) =64a(10) =256a(11) =-1024a(12) =2304a(13) =-3584a(14) =3072a(15) =3072a(16) =-20480a(17) =53248a(18) =-94208a(19) =106496a(20) =0a(21) =-376832a(22) =1179648a(23) =-2359296a(24) =3211264a(25) =-1703936a(26) =-6029312a(27) =24903680a(28) =-56623104a(29) =89128960