Add different class every second and third in WordPress Widget

Modify $before_widget from Widget Class

/**
 * Modify before_widget from Widget Class
 */
if ( !function_exists( 'pixicleaner_filter_dynamic_sidebar_params' ) ) :
function pixicleaner_filter_dynamic_sidebar_params($params){

    static $sidebar_widget_count = array();
    $sidebar_id = $params[0]["id"];

    if ( $sidebar_id == 'pixicleaner_footer_widgets' ) :

	    if (! isset($sidebar_widget_count[$sidebar_id])){
	        $sidebar_widget_count[$sidebar_id] = 0;
	    }
	    $before_widget = $params[0]['before_widget'];

	    $class = ($sidebar_widget_count[$sidebar_id] % 4 == 1) ? "pixicleaner__spcial_widget col-md-2" : "";
	    $class .= ($sidebar_widget_count[$sidebar_id] % 4 == 2) ? "pixicleaner__spcial_widget col-md-2" : "";
	    $class .= " pixicleaner-in-$sidebar_id";
	    $before_widget = str_replace("class=\"", 
	        "class=\"$class ", $before_widget);
	    $params[0]['before_widget'] = $before_widget;
	    $sidebar_widget_count[$sidebar_id]++;
	
	endif;

    return $params;
}
endif;
add_filter("dynamic_sidebar_params", "pixicleaner_filter_dynamic_sidebar_params");