Numbers k such that 60*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

a(0) =0a(1) =1a(2) =5a(3) =7a(4) =8a(5) =10a(6) =19a(7) =22a(8) =40a(9) =62a(10) =65a(11) =118a(12) =121a(13) =148a(14) =251a(15) =283a(16) =304a(17) =591a(18) =745a(19) =874a(20) =1203a(21) =1363a(22) =2239a(23) =2402a(24) =5105a(25) =5775a(26) =5812a(27) =12455a(28) =14234a(29) =39605