115617domain: NAppears in sequencesNumbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 40.at n=16A031718a(n) = 289*n^2 + 17.at n=20A158585Number of (n+1) X (2+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.at n=13A251143