102492domain: NAppears in sequencesNumbers k such that 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=11A099416a(n) = number of primes <= !n, where !n is subfactorial n.at n=9A126701Limit of rows, when read in reverse, of triangle A227372.at n=28A227377