Numbers k such that 3*10^k + 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102976
Numbers k such that 3*10^k + 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =5a(2) =71a(3) =112a(4) =115a(5) =173a(6) =263a(7) =310a(8) =358a(9) =10499a(10) =22925a(11) =37957a(12) =254195a(13) =463649
External references
- oeis: A102976