127656domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 57 ones.at n=17A031825Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=26A207020G.f. satisfies: A(x) = A( x/A(x) )^2 / (1+x).at n=7A245307