Numbers k such that (3^k + 1)/4 is prime.

Terms

a(0) =3a(1) =5a(2) =7a(3) =13a(4) =23a(5) =43a(6) =281a(7) =359a(8) =487a(9) =577a(10) =1579a(11) =1663a(12) =1741a(13) =3191a(14) =9209a(15) =11257a(16) =12743a(17) =13093a(18) =17027a(19) =26633a(20) =104243a(21) =134227a(22) =152287a(23) =700897a(24) =1205459a(25) =1896463a(26) =2533963a(27) =2674381a(28) =7034611