350269895domain: NAppears in sequencesNumerators of continued fraction convergents to sqrt(648).at n=10A042244a(n) = ((5+sqrt(2))*(1+sqrt(2))^n + (5-sqrt(2))*(1-sqrt(2))^n)/2.at n=21A162268Numbers k such that k^2 + 23 is twice a square.at n=21A387549