Perl 6! :) (code slightly adapted to run under Pugs)
#!/usr/bin/perl6
use v6;
# ceil() not yet implemented in Pugs
sub ceil ($n) { int($n) + ($n > int($n) ?? 1 :: 0) }
my $n = 10;
my $discrete = ceil($n ** (1/3));
my $r = any 0..$discrete-1;
my $g = any 0..$discrete-1;
my $b = any 0..$discrete-1;
# Now $r,$g,$b are Junctions containing all the possible values of
# red/green/blue.
$r = int( (1-$r/$discrete) * 255 );
$g = int( (1-$g/$discrete) * 255 );
$b = int( (1-$b/$discrete) * 255 );
# $color is a Junction containing all colors as "(red, green, blue)".
my $color = "($r, $g, $b)";
# Finally, print $color.
for $color -> $x { say $x }
Update: Hand-rolled ceil was wrong, fixed (thanks japhy!).