Numbers n such that 2*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A102959
Numbers n such that 2*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =4a(2) =34a(3) =36a(4) =42a(5) =52a(6) =163a(7) =208a(8) =216a(9) =1417a(10) =14646a(11) =22794a(12) =25648a(13) =32515a(14) =51421
External references
- oeis: A102959