293989domain: 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 72.at n=7A031660Numbers n such that p(n) + p(n+1) is a square and n is prime.at n=19A064398Prime numbersat n=25530