

A271907


Size of the largest subset S of the points of an n X n square grid such that no three of the points of S form an isosceles triangle.


3




OFFSET

1,2


COMMENTS

S must not contain 3 points A,B,C such that AB = BC.
For example, this configuration is forbidden:
O O O B
O O O O
A O O O
O C O O
It appears that this is simply a(n) = 2n2 for n>1, and if so this entry may be replaced by a comment in A271914 and A271906, and this Anumber recycled.


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

Illustration for a(3) = 4:
O X X
X O O
X O O
Illustration for a(8) = 14:
O X X X X X O X
X O O O O O O X
X O O O O O O O
X O O O O O O O
X O O O O O O O
X O O O O O O O
O O O O O O O O
X X O O O O O O


CROSSREFS

Cf. A271906, A227133.
Main diagonal of A271914.
Sequence in context: A076428 A055958 A241142 * A069816 A088116 A100817
Adjacent sequences: A271904 A271905 A271906 * A271908 A271909 A271910


KEYWORD

nonn,more


AUTHOR

Giovanni Resta and N. J. A. Sloane, Apr 22 2016


STATUS

approved



