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The graphs also have n edges.
Table of n, a(n) for n=1..15.
a(5)=1, a 4-cycle plus a pendant edge.
Sequence in context: A240413 A073705 A121158 * A032772 A189732 A174933
Adjacent sequences: A214647 A214648 A214649 * A214651 A214652 A214653
David Bevan, Jul 24 2012