117310domain: NAppears in sequencesTriangle T(n,k) of the number of digraphs with a source on n labeled nodes with k arcs, k=0..n*(n-1).at n=32A057274a(n) = 9 + floor( Sum_{j=1..n-1} a(j)/3 ).at n=33A120154Numbers k such that k and k^2 use only the digits 0, 1, 3, 6 and 7.at n=23A136848