A217004 Numbers arising in computing the Turan function of cycles of length 4.

273, 307, 381, 553, 651, 757, 871, 993, 1057, 1407, 1723, 1893, 2257, 2451, 2863, 3541, 3783, 4161, 4557, 5113, 5403, 6321, 6643, 6973, 8011, 9507, 10303, 10713, 11557, 11991, 12883, 14763, 15751, 16257, 16513, 17293, 18907, 19461, 22351, 22953, 24807, 26733, 28057, 28731, 30103

Offset

1,1

Links

Table of n, a(n) for n=1..45.

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

Cf. A000961, A002061.

Sequence in context: A043804 A043812 A043821 * A256638 A338557 A347882

Adjacent sequences: A217001 A217002 A217003 * A217005 A217006 A217007

Keyword

nonn,easy

Author

Jonathan Vos Post, Sep 22 2012

Status

approved