a(n) = 4a(n-1) - 6a(n-2) + 4a(n-3), n > 3; a(0) = 3, a(1) = 2, a(2) = a(3) = 0.

Terms

a(0) =3a(1) =2a(2) =0a(3) =0a(4) =8a(5) =32a(6) =80a(7) =160a(8) =288a(9) =512a(10) =960a(11) =1920a(12) =3968a(13) =8192a(14) =16640a(15) =33280a(16) =66048a(17) =131072a(18) =261120a(19) =522240a(20) =1046528a(21) =2097152a(22) =4198400a(23) =8396800a(24) =16785408a(25) =33554432a(26) =67092480a(27) =134184960a(28) =268402688a(29) =536870912