a(n) is the smallest prime >= 6^n.

Terms

a(0) =2a(1) =7a(2) =37a(3) =223a(4) =1297a(5) =7789a(6) =46663a(7) =279941a(8) =1679627a(9) =10077721a(10) =60466181a(11) =362797091a(12) =2176782371a(13) =13060694051a(14) =78364164101a(15) =470184984667