531377domain: NAppears in sequencesa(n) = 9^n - 2^n.at n=6A191465Monotonic ordering of nonnegative differences 9^i-4^j, for 40>= i>=0, j>=0.at n=33A192170Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x+487)^2 = y^2.at n=13A207076