login
A128241
Number of n-node (unlabeled) connected graphs with girth 4.
4
0, 1, 2, 11, 41, 220, 1243, 9368, 89049, 1135894, 19381407, 445505570, 13741579905, 566739127723, 31124921885829
OFFSET
3,3
FORMULA
a(n) = A024607(n) - A126757(n). - Martin Fuller, May 01 2015
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Keith Briggs, May 05 2007
EXTENSIONS
Corrected and extended by Martin Fuller, May 01 2015
STATUS
approved