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A186744
Number of connected regular simple graphs on n vertices with girth exactly 4.
2
0, 0, 0, 0, 1, 0, 1, 0, 3, 0, 8, 2, 34, 31, 330, 1607, 17970, 193906, 2867269, 32674056, 1581626328, 6705889815
OFFSET
0,9
FORMULA
a(n) = A186724(n) - A186725(n).
CROSSREFS
Sequence in context: A197416 A197512 A232272 * A200507 A348333 A296042
KEYWORD
nonn,more,hard
AUTHOR
Jason Kimberley, Apr 03 2012
STATUS
approved