A210715 Number of disconnected regular simple graphs on n vertices with girth exactly 5.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 6, 6, 9, 9, 22, 13, 82, 18, 618, 26, 7164, 36, 107862, 50, 1876730, 70, 35924810, 95, 741405213, 131, 16356067216, 323, 383931367731, 132977

Offset: 0

Author

Jason Kimberley, Dec 10 2012

Keywords

• nonn
• more
• hard

Links

• Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth exactly g

Formula

a(n) = A185215(n) - A185216(n).