127020domain: NAppears in sequencesEven square pyramidal numbers.at n=35A015222Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 2,1,3.at n=5A037637Number of integers k such that phi(k) = 10^n.at n=31A072074a(n) = n*(2*n + 1)*(4*n + 1)/3.at n=36A258582