9138529domain: NAppears in sequencesPerfect squares which can be written neither as a^2+b^2, nor as a^2+2*b^2, nor as a^2+3*b^2, nor as a^2+7*b^2, with a > 0 and b > 0.at n=28A216408Squares whose second arithmetic derivative is a square.at n=24A348425