110171domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 53 ones.at n=16A031821a(n) = a(n-1) + Sum_{k=0..floor(log_2(n-1))} a(2^k), a(1) = 1.at n=40A133147Numbers such that the digital sums in bases 2, 3, 5 and 10 all are equal.at n=25A135128