Numbers k such that 40*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A056661
Numbers k such that 40*R_k + 3 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) =8a(5) =11a(6) =29a(7) =31a(8) =182a(9) =296a(10) =491a(11) =41315
External references
- oeis: A056661