Numbers k such that 2*10^k + 3*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.

A056701

Numbers k such that 2*10^k + 3*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =10a(6) =16a(7) =22a(8) =53a(9) =91a(10) =94a(11) =106a(12) =138a(13) =210a(14) =282a(15) =522a(16) =597a(17) =1049a(18) =2227a(19) =6459a(20) =10582a(21) =18895a(22) =41269a(23) =50702a(24) =53185a(25) =59796a(26) =101395a(27) =116514a(28) =137551a(29) =153116

External references