login
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
1, 2, 4, 6, 8, 10, 12, 14, 16, 18
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) = 2n-2 for n>1, and if so this entry may be replaced by a comment in A271914 and A271906, and this A-number recycled.
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
Main diagonal of A271914.
Sequence in context: A319747 A055958 A241142 * A069816 A088116 A100817
KEYWORD
nonn,more
AUTHOR
STATUS
approved