[seqfan] Max no. of edges in graph with no 4-cycles

Neil Sloane njasloane at gmail.com
Mon Mar 7 17:45:10 CET 2022

Let b(n) be the maximum number of edges in a graph on n nodes that contains
no 4-cycle.

It seems to start (for n>=1) 0, 1, 3, 4, 7, 9?

Is it missing from the OEIS?

This question came up because M S Smith seems to have proved that b(n) is
an upper bound on Stan Wagon's Problem of the Week #1321 (and also on
A347301). Happy to send anyone who is interested a copy of Smith's email.

Best regards

Neil J. A. Sloane, Chairman, OEIS Foundation.
Also Visiting Scientist, Math. Dept., Rutgers University,
Email: njasloane at gmail.com

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