Back in the olden days, airlines used to have fun with flight numbers --
NW777 MSP-LAS
NW1492 MSP-CMH
NW1776 MSP-PHL
And 711 was a flight to/from LAS also.
And used to be, but not that consistent now, but
ATL-DCA flights -- 1x38
DCA-ATL flights -- 1x39