

A350547


Maximum size of a set of points taken from a hexagonal section of a hexagonal grid with side length n such that no three selected points form an equilateral triangle.


0




OFFSET

0,2


COMMENTS

The hexagon with side length n has n+1 points along each edge and contains a total of A003215(n) points.
The following lower bounds are known:
a(7) >= 44;
a(8) >= 52;
a(9) >= 60.
All currently known values and lower bounds can be achieved by a configuration with reflective symmetry.


LINKS



EXAMPLE

For n = 4 the a(4) = 22 solution, unique up to rotation, is:
.
o x x o x
x x o o o x
x o o o o x o
o o o o o o x x
x o o o o o o o x
x x o o o o o o
o x o o o o x
x o o o x x
x o x x o
.


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



