Numbers k such that 3^k - 4 is prime.

Terms

a(0) =2a(1) =3a(2) =5a(3) =21a(4) =31a(5) =37a(6) =41a(7) =53a(8) =73a(9) =101a(10) =175a(11) =203a(12) =225a(13) =455a(14) =557a(15) =651a(16) =1333a(17) =4823a(18) =20367a(19) =32555a(20) =52057a(21) =79371a(22) =267267a(23) =312155