90075015625domain: NAppears in sequencesNumbers k = p_i^e_i * p_j^e_j such that i/e_i + j/e_j = 1 for e_i, e_j >= 1, p_i, p_j distinct prime numbers.at n=19A387978Odd positive integers whose canonical prime factorization p_1^e_1*...*p_r^e_r satisfies that {p_1, ..., p_r, e_1, ..., e_r} is a set of 2*r consecutive integers.at n=20A392045