progression.php

<?php
/**
 * Created by PhpStorm.
 * User: vesper
 * Date: 15/08/2017
 * Time: 14:21
 */

function progression($x = 4, $n = 0, $count = 3) {
    $x = $x + (2 * (3 ** $n));
    echo "x = ".$x.PHP_EOL;
    echo "n = ".$n.PHP_EOL;
    $n++;

    if (! ($count < 0)) {
        echo "count: ".$count.PHP_EOL;
        $count--;

        return progression($x, $n, $count);
    } else return 1;
}

progression();