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A128237
Number of n-node (unlabeled) graphs with girth 4.
5
0, 1, 3, 15, 59, 296, 1604, 11303, 102108, 1250114, 20738069, 467523871, 14230096759, 581439661069, 31720637440030
OFFSET
3,3
FORMULA
a(n) = A006785(n) - A006787(n).
CROSSREFS
KEYWORD
nonn
AUTHOR
Keith Briggs, May 05 2007
EXTENSIONS
Corrected and extended by Martin Fuller, May 01 2015
STATUS
approved