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

Terms

a(0) =0a(1) =1a(2) =2a(3) =0a(4) =4a(5) =4a(6) =4a(7) =12a(8) =12a(9) =20a(10) =36a(11) =44a(12) =76a(13) =116a(14) =164a(15) =268a(16) =396a(17) =596a(18) =932a(19) =1388a(20) =2124a(21) =3252a(22) =4900a(23) =7500a(24) =11404a(25) =17300a(26) =26404a(27) =40108a(28) =61004a(29) =92916