Scopa - distribution of cards

#!/usr/bin/env php
<?php

if (! isset($argv[1])) {
    echo 'Usage scopa.php number' . PHP_EOL;
    exit;
}

// offical for 3 players, 3 in hand, 4 on table
//    r = (-i k-m+40)/(i k)
$totalCards = 40;
$minRounds = 3;
$minInHand = 3;
$minOnTable = 4;

$numberOfPlayers = $argv[1];

if ($numberOfPlayers < 2) {
    echo 'Number of players must be at least 2.' . PHP_EOL;
    exit;
}

echo "Results for $numberOfPlayers players."  . PHP_EOL;
for ($cardsOnTable = $minOnTable; $cardsOnTable < $totalCards; $cardsOnTable++) {
    for ($cardsInHand = $minInHand; $cardsInHand < $totalCards; $cardsInHand++) {
        $rounds =
            (-1 * $numberOfPlayers * $cardsInHand - $cardsOnTable + $totalCards) /
            ($numberOfPlayers * $cardsInHand);

        if (is_int($rounds) && $rounds >= $minRounds) {
            echo "Rounds $rounds, On table: $cardsOnTable, In hand: $cardsInHand" . PHP_EOL;
        }
    }
}