OFFSET
0,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 0..26
EXAMPLE
Configurations of 0,1,2,3 or 4 kings on an 2 X 2 chessboard and the number of mutual attacks:
.. .. .. K. .K .. K. KK .K .K K. K. .K KK KK KK
.. K. .K .. .. KK K. .. .K K. .K KK KK .K K. KK
0 0 0 0 0 1 1 1 1 1 1 3 3 3 3 6
From 16 configurations is 11 with no more than 1 mutual attack, a(2)=11.
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 04 2008
EXTENSIONS
Example added by Vaclav Kotesovec, Oct 20 2014
Additional terms from R. H. Hardin, Feb 13 2016
STATUS
approved