Numbers n such that 6*10^n + 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103033

Numbers n such that 6*10^n + 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =1a(1) =3a(2) =4a(3) =5a(4) =6a(5) =10a(6) =13a(7) =58a(8) =96a(9) =178a(10) =360a(11) =420a(12) =455a(13) =1008a(14) =1517a(15) =2975a(16) =3999a(17) =5425a(18) =10819a(19) =16036a(20) =32076a(21) =47237a(22) =111385a(23) =190935

External references