%N Number of Eulerian orientations in the n-cocktail party graph.
%C An Eulerian orientation of a graph is an orientation of the edges such that every vertex has in-degree equal to out-degree.
%C The corresponding sequence for the complete graph on 2n+1 vertices is A007079.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CocktailPartyGraph.html">Cocktail Party Graph</a>
%Y Cf. A007079, A297383.
%A _Andrew Howroyd_, May 22 2020