Numbers k such that 10*3^k - 1 is prime.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =8a(5) =10a(6) =14a(7) =20a(8) =22a(9) =26a(10) =30a(11) =38a(12) =39a(13) =49a(14) =54a(15) =58a(16) =70a(17) =81a(18) =84a(19) =87a(20) =102a(21) =111a(22) =140a(23) =159a(24) =207a(25) =224a(26) =328a(27) =358a(28) =360a(29) =447