631362domain: NAppears in sequencesLet r, s, t, u be four permutations of the set { 1, 2, 3, ..., n }; a(n) = minimal value of Sum_{i=1..n} r(i)*s(i)*t(i)*u(i).at n=29A070736Number of labeled directed multigraphs (without loops) with n arcs and no vertex of degree 0.at n=5A121137