686784

Appears in sequences

• v(n+1)/v(n), where v=A203679.at n=2A203680
• Triangular array read by rows. T(n,k) is the number of 2-colored labeled graphs on n nodes with exactly k edges; n >= 0, 0 <= k <= A002620(n).at n=47A228890
• Irregular triangular array read by rows: T(n,k) is the number of 2-colored simple labeled graphs on n nodes that have exactly k edges, 0<=k<=A002620(n), n>=1.at n=46A241669
• Number of 4-cycles in the n X n rook complement graph.at n=7A291910