It's actually pretty readable once it's properly formatted (and once you've run it to see what it does). It runs fine with strict and warnings, too. I wasn't familiar with the use of "%*d" in sprintf. 
#! /usr/bin/perl

use strict;
use warnings;

$/ = length( $" = int <STDIN> ) + 1;
for $! ( 1 .. $" ) {
    print $_< $" + 1 - $! ?
                " " x $/
        : $_ <= $" ?
                sprintf "%*d", $/, $" + 1 - $_
        : $_ <= $" + $! - 1 ?
                sprintf "%*d", $/, abs $" - 1 - $_
        : $_ == 2 * $" ?
                "\n"
        :
                ""
        foreach ( 1 .. ( 2 * $" ) );
}

[download]
We can interpret the ternary operators as being the equivalent of a C switch() statement. The first case of the switch() prints out the leading spaces needed to maintain the pyramid shape. The second case prints out the numbers from $! down to 1. The third case prints out the numbers from 2 up to $!. The fourth case prints the final newline. The default case prints nothing.

In reply to Re: A first attempt at obfuscation. by jdalbec
in thread A first attempt at obfuscation. by Pic

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