Powers of 8: a(n) = 8^n.

Terms

a(0) =1a(1) =8a(2) =64a(3) =512a(4) =4096a(5) =32768a(6) =262144a(7) =2097152a(8) =16777216a(9) =134217728a(10) =1073741824a(11) =8589934592a(12) =68719476736a(13) =549755813888