UA 1815 then DL 3876 at Denver
Tampa → Denver → Austin
Timetable, Denver time
10:08UA 1815 from Tampa at the gate
09:42DL 3876 to Austin leaves the gate
23 h 34 apart on the timetable, overnight
DL 3876 leaves 23 h 34 after UA 1815 arrives on the timetable: more than half a day, so not a connection we count.