53492domain: NAppears in sequencesNumbers k such that 5*10^k + 9 is prime.at n=15A103004Number of arrangements of 4 nonzero numbers x(i) in -n..n with the sum of trunc(x(i)/x(i+1)) equal to zero.at n=12A189547Numbers n such that x^n * (x+1)^(n-1) + 1 is irreducible over GF(2).at n=23A268274