The number of labeled directed graphs (with self loops allowed) on n nodes of at most two colors, where no edge connects nodes of distinct colors.

A197356

The number of labeled directed graphs (with self loops allowed) on n nodes of at most two colors, where no edge connects nodes of distinct colors.

Terms

    a(0) =1a(1) =4a(2) =40a(3) =1216a(4) =140800a(5) =68583424a(6) =138280960000

External references