A Graph containing an Eulerian Circuit. An undirected Graph is Eulerian Iff every Vertex has Even Degree. A Directed Graph is Eulerian Iff every Vertex has equal Indegree and Outdegree. A planar Bipartite Graph is Dual to a planar Euler graph and vice versa. The number of Euler graphs with nodes are 1, 1, 2, 3, 7, 16, 54, 243, ... (Sloane's A002854).

**References**

Sloane, N. J. A. Sequence
A002854/M0846
in ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.
*The Encyclopedia of Integer Sequences.* San Diego: Academic Press, 1995.

© 1996-9

1999-05-25