Most widely copied riffs in popular music

How about those 3-same-note endings by Ellington, with the last one anticipating the beat?

I think you mean the Basie ending.

I associate Ellington with the “A Train” ending: | 8 - 3 - 4 - 4# | 5 - 6 - 7 - 8 | R~~~~>

The “Day Tripper” riff is also used on the John Mayall and the Bluesbreakers (with Clapton) version of “What’d I Say” on the Beano album. http://www.youtube.com/watch?v=XW91zp0qNNg 3:36 after the drum solo