Y by Amir Hossein, mssmath, Davi-8191, AopsUser101, Adventure10, megarnie, Mango247
Let
be a positive integer. Each point
in the plane, where
and
are non-negative integers with
, is coloured red or blue, subject to the following condition: if a point
is red, then so are all points
with
and
. Let
be the number of ways to choose
blue points with distinct
-coordinates, and let
be the number of ways to choose
blue points with distinct
-coordinates. Prove that
.
















This post has been edited 4 times. Last edited by orl, Sep 27, 2005, 4:57 PM