Numbers k such that 7*10^k + 6*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

A103065

Numbers k such that 7*10^k + 6*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =1a(1) =2a(2) =3a(3) =6a(4) =8a(5) =18a(6) =19a(7) =21a(8) =32a(9) =48a(10) =65a(11) =72a(12) =99a(13) =120a(14) =201a(15) =308a(16) =717a(17) =968a(18) =1344a(19) =2132a(20) =3567a(21) =3968a(22) =8327a(23) =10598a(24) =12465a(25) =15875a(26) =18895a(27) =28611a(28) =29418a(29) =83693

External references