Three crooks who invaded a Brooklyn apartment at gunpoint, tied up a resident and stole his property last week remain at large, police reported. The NYPD on Jan. 15 released video footage of the invaders moments before they busted into a sixth-floor apartment on East 18th Street between Albemarle Road and Tennis Court in Prospect Park South on Jan. 8 at 4:50 pm. The trouble began, law enforcement sources said, moments after an unidentified female suspect delivered food to a 38-year-old man inside the sixth-floor apartment.  Then, cops said, two men appeared at the victim’s doorway and knocked. When he …