British Airways AARP discount tickets from Los Angeles to Copenhagen, Denmark are $420 round trip for travel departures January to May and mid-August to October 2018.
Google Flights shows ticket prices as low as $427, mostly flying Finnair via Helsinki on return. British Airways AARP reduces these ticket prices to $420 round trip from $456 for BA operated one-stop flights via London Heathrow.
These ticket prices are even lower than any OTA deals through Momondo.com for dates I searched.
British Airways AARP discount ticket
Los Angeles LAX – London LHR – Copenhagen CPH – LHR – LAX
$419.87 round trip Thu August 23 – Monday Sep 3 (Labor Day)