a(n) = 8*a(n-2) for n > 2; a(1) = 1, a(2) = 6.

Terms

a(0) =1a(1) =6a(2) =8a(3) =48a(4) =64a(5) =384a(6) =512a(7) =3072a(8) =4096a(9) =24576a(10) =32768a(11) =196608a(12) =262144a(13) =1572864a(14) =2097152a(15) =12582912a(16) =16777216a(17) =100663296a(18) =134217728a(19) =805306368a(20) =1073741824a(21) =6442450944a(22) =8589934592a(23) =51539607552a(24) =68719476736a(25) =412316860416