Numbers k such that 10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102937
Numbers k such that 10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =1a(2) =2a(3) =5a(4) =7a(5) =19a(6) =20a(7) =28a(8) =58a(9) =250a(10) =397a(11) =7591a(12) =32716a(13) =70978a(14) =83587a(15) =140693
External references
- oeis: A102937