<?php


error_reporting(-1);

function generateCombinations($n, $values)
{
    if (count($values) == $n) {
        yield $values;
        return $values;
    }
    for ($i = 1; $i < 7; $i++) {
        yield from generateCombinations($n, array_merge($values, [$i]));
    }

}


$generator = generateCombinations(3, []);
foreach ($generator as $value) {
    print_r($value);
}