Create a list of event ID's with recurring events added only once

I have been finding many different solutions for listing events but limiting recurring events to only show once. Here is one solution. In this case I needed to output the event Post ID’s to use in a slider plugin.

//Create a list of event IDs, with recurring events only added one time
   if (class_exists('EM_Events')) {
//assign non-recurring event IDs to an array
    $notRecur = EM_Events::get( array('scope' => 'future' ));
	foreach($notRecur as $EM_Event){
        if (!$EM_Event->is_recurrence()){
	   $ID_NotRecur[]= $EM_Event->output('#_EVENTPOSTID'); }  }
//assign recurring event template IDs to an array
    $Recur = EM_Events::get( array('scope' => 'future' ,
        'recurring'=>'1' ));
        foreach($Recur as $EM_Event){
	   $ID_Recur[]= $EM_Event->output('#_EVENTPOSTID'); }  }
//merge the arrays
	$ID_EMPost = array_merge($ID_NotRecur, $ID_Recur);
//check the output
echo implode (' , ', $ID_EMPost);

Note: This gets the post id of the ‘event-recurring’ custom post type recurring event template, rather than an instance of a recurring event.
https://wordpress.org/plugins/events-manager/