OFFSET
1,1
LINKS
Z. Füredi, Graphs without quadrilaterals, J. Combin. Theory (A) 34 (1983), 187-190.
Z. Füredi, On the number of edges of quadrilateral-free graphs, J. Combin. Theory (B) 68 (1996), 1-6.
Oleg Pikhurko, A Note on the Turan Function of Even Cycles, Proc Amer Math Soc, 140 (2012) 3687-3992.
FORMULA
a(n) = q^2+q+1 where q=A000961(n+10). - R. J. Mathar, Jul 12 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Sep 22 2012
STATUS
approved