Squares in a checkerboard

checkerboard.pl

#!/usr/bin/perl

use strict;
use warnings;

my $m = shift @ARGV;

my $sqrs = 0;

#
#   n=m
#    (
#   /   (m-n+1)^2
#  )
# n=1
for my $n (1..$m) {
    $sqrs += ($m - $n + 1) * ($m - $n + 1);
}

print "Checkerboard of ($m x $m) has $sqrs squares\n";