Numbers k such that (31*10^k - 121) / 9 is prime.

Terms

a(0) =2a(1) =6a(2) =8a(3) =21a(4) =66a(5) =84a(6) =86a(7) =89a(8) =93a(9) =104a(10) =170a(11) =249a(12) =273a(13) =413a(14) =824a(15) =1392a(16) =1589a(17) =1679a(18) =3125a(19) =3185a(20) =3482a(21) =4089a(22) =4772a(23) =5138a(24) =5738a(25) =54761a(26) =86364