70986domain: NAppears in sequencesa(n) = Sum_{1 <= x_1 <= x_2 <= x_3 <= x_4 <= n} gcd(x_1, x_2, x_3 , x_4, n).at n=33A343518Numbers that are the sum of nine fifth powers in three or more ways.at n=18A345620Numbers that are the sum of nine fifth powers in exactly three ways.at n=17A346338