A186745 Number of connected regular simple graphs on n vertices with girth exactly 5.

0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 2, 0, 8, 0, 48, 0, 450, 1, 5753, 8, 90684, 3917, 1736764, 4131991, 163457964, 4018022149, 119021971348

Offset: 0

Author

Jason Kimberley, Apr 03 2012

Keywords

• nonn
• more
• hard

Links

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

Formula

a(n) = A186725(n) - A186726(n).

Extensions

a(26) corrected by the author, due to correction of A186725, May 19 2017