a(n) = 8*a(n-2) for n > 2; a(1) = 1, a(2) = 12.

Terms

a(0) =1a(1) =12a(2) =8a(3) =96a(4) =64a(5) =768a(6) =512a(7) =6144a(8) =4096a(9) =49152a(10) =32768a(11) =393216a(12) =262144a(13) =3145728a(14) =2097152a(15) =25165824a(16) =16777216a(17) =201326592a(18) =134217728a(19) =1610612736a(20) =1073741824a(21) =12884901888a(22) =8589934592a(23) =103079215104a(24) =68719476736a(25) =824633720832