$args = array(
    'type' => 'post',
    'hide_empty' => 0,
    'hierarchical' => 1,
    'taxonomy' => 'category',
    'pad_counts' => false
);
$categories = get_categories($args);
foreach($categories as $category) { 
    echo '';
    if($category->parent != 0){ // If this is a subcategory
        echo "  $category->name";
    } else {
        echo "$category->name";
    }
    echo "";
    echo '';
}