Online PHP editor | refs for m12ke

<?php function create_word(string $alphabet, int $index): string { $base = mb_strlen($alphabet); $fix = 1; $length = 1; foreach (range(1, $base) as $k) { $pow = pow($base, $k); if ($fix + $pow <= $index) { $fix += $pow; $length++; } else { break; } } $template = sprintf("%0{$length}d", base_convert($index - $fix, 10, $base)); $replace = implode('', range(0, $base)); return strtr($template, $replace, $alphabet); } for ($i = 1; $i <= 81; $i++) { echo $i . ' = '. create_word("abc", $i) . \PHP_EOL; }