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

Terms

a(0) =3a(1) =2a(2) =0a(3) =0a(4) =4a(5) =12a(6) =24a(7) =44a(8) =84a(9) =168a(10) =340a(11) =684a(12) =1368a(13) =2732a(14) =5460a(15) =10920a(16) =21844a(17) =43692a(18) =87384a(19) =174764a(20) =349524a(21) =699048a(22) =1398100a(23) =2796204a(24) =5592408a(25) =11184812a(26) =22369620a(27) =44739240a(28) =89478484a(29) =178956972