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

Terms

a(0) =1a(1) =0a(2) =4a(3) =-8a(4) =32a(5) =-96a(6) =320a(7) =-1024a(8) =3328a(9) =-10752a(10) =34816a(11) =-112640a(12) =364544a(13) =-1179648a(14) =3817472a(15) =-12353536a(16) =39976960a(17) =-129368064a(18) =418643968a(19) =-1354760192a(20) =4384096256a(21) =-14187233280a(22) =45910851584a(23) =-148570636288a(24) =480784678912