Numbers k such that R_(k+2) + 6*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A256932
Numbers k such that R_(k+2) + 6*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =8a(2) =9a(3) =23a(4) =54a(5) =72a(6) =92a(7) =402a(8) =405a(9) =651a(10) =860a(11) =897a(12) =2691a(13) =3887a(14) =4665a(15) =4971a(16) =5271a(17) =8931a(18) =9953a(19) =10566a(20) =10907a(21) =11955a(22) =22467a(23) =66755a(24) =153810a(25) =169337a(26) =224061
External references
- oeis: A256932