A128241 Number of n-node (unlabeled) connected graphs with girth 4.

0, 1, 2, 11, 41, 220, 1243, 9368, 89049, 1135894, 19381407, 445505570, 13741579905, 566739127723, 31124921885829

Offset: 3

Author

Keith Briggs, May 05 2007

Keywords

• nonn
• more

Crossrefs

Cf. A024607, A126757.

Cf. A128041, A128042, A128236-A128243.

Formula

a(n) = A024607(n) - A126757(n). - Martin Fuller, May 01 2015

Extensions

Corrected and extended by Martin Fuller, May 01 2015