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

Terms

a(0) =1a(1) =0a(2) =0a(3) =4a(4) =-8a(5) =16a(6) =-16a(7) =0a(8) =64a(9) =-192a(10) =384a(11) =-512a(12) =256a(13) =1024a(14) =-4096a(15) =9216a(16) =-14336a(17) =12288a(18) =12288a(19) =-81920a(20) =212992a(21) =-376832a(22) =425984a(23) =0a(24) =-1507328a(25) =4718592a(26) =-9437184a(27) =12845056a(28) =-6815744a(29) =-24117248