29639domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 41 ones.at n=8A031809a(n) = n*(n^2 - 1)/2 - 1.at n=37A117560Number of subsets of {1, 2, ..., n} containing n and having <=9 pairwise coprime elements.at n=30A186993Smallest k such that A257743(k)=n.at n=21A257744