#!/opt/perl-5.10.0/bin/perl                                                                                                                                                
use strict;
use warnings;
use feature ':5.10';
use Text::Table;

for ( my $width = 15; $width == 15; ++$width ) {
    my $table = Text::Table->new;
    my $nth   = 0;
    my $total = ( $width**2 - $width ) / 2;
    for my $III ( 1 .. $width ) {
        my @row = ('.') x $III;
        for my $JJJ ( $III + 1 .. $width ) {

            my $aha = $width + .5 - sqrt( 2 * ( $total - $nth ) );
            my $row = int $aha;
            my $col = $row + 1 + int( ( $aha - $row ) * ( $width - $row ) );
            push @row, "${row}x$col";
            ++$nth;
        }
        $table->load( \@row );
    }

    say "${width}x$width\n$table";
}