freqCount([1, 4, 4, [1, 1, [1, 2, 1, 1]]], 1);
<?php
function freqCount($arr, $el) {
$depth = 0;
recurse($arr, $el, $depth);
}
function recurse($a, $e, $depth) {
$counter = 0;
$result = [];
foreach($a as $k => $v) {
if(!is_array($v) && $v === $e) {
$counter++;
$result[$depth] = $counter;
} elseif(is_array($v)) {
$depth++;
recurse($v, $e, $depth);
} else {
continue;
}
}
echo "<pre>";
print_r($result);
}