

A229803


Domination number for rook graph HR(n) on a triangular board of hexagonal cells. The rook can move along any row of adjacent cells, in any of the three directions.


1



1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 9
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OFFSET

1,3


COMMENTS

The value for HR(20) was obtained by Rob Pratt, Sep 29 2013, using integerlinear programming.


REFERENCES

J. Konhauser, D. Velleman, S. Wagon, Which Way Did the Bicycle Go? Washington, DC, Math. Assoc. of America, 1996, pp. 169172


LINKS

Table of n, a(n) for n=1..20.
J. DeMaio and H. L. Tran, Domination and independence on a triangular honeycomb chessboard, Coll. Math. J. 44 (2013) 307314.
Stan Wagon, Graph Theory Problems from Hexagonal and Traditional Chess, The College Mathematics Journal, Vol. 45, No. 4, September 2014, pp. 278287


EXAMPLE

For HR(7), the graph can be dominated by the three vertices 6, 11, 26, where we count down from the top.
This graph was called the Queen graph in the DeMaio and Tran paper, but the moves are those of a rook in the classic hexagonal chess game.


CROSSREFS

Cf. A075458, A075324, A075561, A006075.
Sequence in context: A121828 A057357 A308358 * A029123 A025777 A269862
Adjacent sequences: A229800 A229801 A229802 * A229804 A229805 A229806


KEYWORD

nonn,hard,more


AUTHOR

Stan Wagon, Sep 29 2013


STATUS

approved



