

A111731


Minimal size of a complete cap in (Z/nZ)^2.


0




OFFSET

2,1


COMMENTS

A line in (Z/nZ)^2 is any translate of a cyclic subgroup of order n. A subset X of (Z/nZ)^2 is a cap if no three of its points are collinear and X is complete if it is not properly contained in another cap. a(n) is the minimal size of a complete cap in (Z/nZ)^2.


LINKS



FORMULA

If p is the smallest prime divisor of n, max{4, sqrt2p+1/2} <= a(n) <= max{4,p+1}. a(n) = 4 if n is divisible by 2 or 3.


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



