267217domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 33.at n=30A031621a(n) = 24*A138879(n) - A187219(n).at n=24A183012Prime numbersat n=23409