A098851 Number of triangle-free configurations of type (n_3).

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 4, 14, 162, 4713, 157211

Offset

1,18

Links

Table of n, a(n) for n=1..22.

A. Alazemi and A. Betten, Classification of Triangle-Free 22_3 Configurations, International Journal of Combinatorics, Volume 2010, Article ID 767361.

A. Betten, G. Brinkmann and T. Pisanski, Counting symmetric configurations v_3, Discrete Appl. Math., 99 (2000), 331-338.

M. Boben et al., Small triangle-free configurations of points and lines, Discrete Comput. Geom., 35 (2006), 405-427.

Crossrefs

Cf. A001403.

Sequence in context: A162077 A247526 A111266 * A080986 A132555 A129220

Adjacent sequences: A098848 A098849 A098850 * A098852 A098853 A098854

Keyword

nonn,more,hard

Author

N. J. A. Sloane

Extensions

a(22) from Abdullah Alazemi, Sep 05 2021

Status

approved