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

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =-2a(5) =6a(6) =-17a(7) =49a(8) =-141a(9) =406a(10) =-1169a(11) =3366a(12) =-9692a(13) =27907a(14) =-80355a(15) =231373a(16) =-666212a(17) =1918281a(18) =-5523470a(19) =15904198a(20) =-45794313a(21) =131859469a(22) =-379674209a(23) =1093228314a(24) =-3147825473a(25) =9063802210a(26) =-26098178316a(27) =75146709475a(28) =-216376326215a(29) =623030800329