login
A186726
Number of connected regular graphs with n nodes and girth at least 6.
13
1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 6, 1, 33, 1, 386, 1, 7575, 1, 181229, 1, 4624503, 1, 122090549, 1, 3328929974, 1, 93990693868, 26, 2754223099408, 13505
OFFSET
0,15
FORMULA
a(n) = sum of the n-th row of A186716.
EXAMPLE
a(37) = 0 + 0 + 1 + 0 + 13504 = 13505.
CROSSREFS
Connected regular graphs of any degree with girth at least g: A005177 (g=3), A186724 (g=4), A186725 (g=5), this sequence (g=6), A186727 (g=7), A186728 (g=8), A186729 (g=9).
Connected k-regular simple graphs with girth at least 6: this sequence (any k), A186716 (triangle); specific k: A185116 (k=2), A014374 (k=3), A058348 (k=4).
Sequence in context: A368777 A113766 A204992 * A205405 A112623 A130675
KEYWORD
nonn,more,hard
AUTHOR
Jason Kimberley, Nov 23 2011
EXTENSIONS
a(36)-a(37) from Jinyuan Wang, Mar 02 2020
STATUS
approved