130359domain: NAppears in sequencesNumbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 19.at n=18A031697The number of 321- and 2143-avoiding permutations of length n.at n=15A088921a(n) = 361*n^2 + 2*n.at n=18A158309a(n) = n*(n^3 + 2).at n=19A185065