Numbers n such that 6*10^n + 8*R_n - 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103044
Numbers n such that 6*10^n + 8*R_n - 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =4a(2) =10a(3) =13a(4) =178a(5) =304a(6) =331a(7) =502a(8) =744a(9) =1027a(10) =1770a(11) =5305a(12) =55075
External references
- oeis: A103044