Numbers k such that 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A099411
Numbers k such that 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =6a(4) =46a(5) =394a(6) =978a(7) =2586a(8) =2811a(9) =2968a(10) =3642a(11) =4827a(12) =4918a(13) =5592a(14) =5706a(15) =10683a(16) =12891a(17) =14118a(18) =74350a(19) =88680a(20) =162138a(21) =279978
External references
- oeis: A099411