431211domain: NAppears in sequencesA continued fraction.at n=15A001112Denominators of continued fraction convergents to sqrt(648).at n=8A042245a(n) is the number m such that f(sqrt(n)) is in the field Q(sqrt(m)), where f(x) is defined from the continued fraction x = [c(0), c(1), ... ] as [c(0)^2, c(1)^2, ...].at n=46A229959