UA 4544 then LN 744 at Dulles
Providence → Washington → Buffalo
Timetable, Washington time
12:00UA 4544 from Providence at the gate
04:00LN 744 to Buffalo leaves the gate
16 h apart on the timetable, overnight
LN 744 leaves 16 h after UA 4544 arrives on the timetable: more than half a day, so not a connection we count.