Numbers n such that 4*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A102994

Numbers n such that 4*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =9a(4) =14a(5) =24a(6) =45a(7) =49a(8) =73a(9) =74a(10) =232a(11) =338a(12) =397a(13) =504a(14) =1063a(15) =2817a(16) =5305a(17) =16768a(18) =27060

External references