Numbers k such that 30*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =17a(8) =39a(9) =49a(10) =59a(11) =77a(12) =100a(13) =150a(14) =318a(15) =381a(16) =783a(17) =1731a(18) =1917a(19) =8854a(20) =11244a(21) =11959a(22) =12129a(23) =18532a(24) =22717a(25) =23364a(26) =24252a(27) =24548a(28) =25323a(29) =30177