Numbers k such that 10^k + 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102932
Numbers k such that 10^k + 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =1a(2) =2a(3) =4a(4) =5a(5) =12a(6) =60a(7) =109a(8) =181a(9) =245a(10) =412a(11) =887a(12) =2477a(13) =2918a(14) =4622a(15) =6240a(16) =6253a(17) =7684a(18) =14630a(19) =20932a(20) =49801a(21) =254107a(22) =275671a(23) =380056
External references
- oeis: A102932