Smallest prime >= 8^n.

Terms

a(0) =2a(1) =11a(2) =67a(3) =521a(4) =4099a(5) =32771a(6) =262147a(7) =2097169a(8) =16777259a(9) =134217757a(10) =1073741827a(11) =8589934609a(12) =68719476767a(13) =549755813911