A128237 Number of n-node (unlabeled) graphs with girth 4.

0, 1, 3, 15, 59, 296, 1604, 11303, 102108, 1250114, 20738069, 467523871, 14230096759, 581439661069, 31720637440030

Offset: 3

Author

Keith Briggs, May 05 2007

Keywords

• nonn

Crossrefs

Cf. A006785, A006787.

Cf. A128041, A128042, A128236-A128243.

Formula

a(n) = A006785(n) - A006787(n).

Extensions

Corrected and extended by Martin Fuller, May 01 2015