a(n) = ceiling(8^n/n).

Terms

a(0) =8a(1) =32a(2) =171a(3) =1024a(4) =6554a(5) =43691a(6) =299594a(7) =2097152a(8) =14913081a(9) =107374183a(10) =780903145a(11) =5726623062a(12) =42288908761a(13) =314146179365