Numbers k such that (3^k - 1)/2 is prime.

Terms

a(0) =3a(1) =7a(2) =13a(3) =71a(4) =103a(5) =541a(6) =1091a(7) =1367a(8) =1627a(9) =4177a(10) =9011a(11) =9551a(12) =36913a(13) =43063a(14) =49681a(15) =57917a(16) =483611a(17) =877843a(18) =2215303a(19) =2704981a(20) =3598867a(21) =7973131a(22) =8530117