248310domain: NAppears in sequencesNumber of ways of writing n as the sum of 9 triangular numbers.at n=38A226253Let s(k) denote the sum of the even proper divisors of k. The sequence lists the pairs of numbers (x, y) such that s(x) = y and s(y) = x.at n=30A279812List of ordered pairs (x, y) from A279812.at n=27A279950