Artist: Usher
Song: Yeah
Tabber: Ben Richardson (Fx7Dude)

I don't really know how to write keyboard tab but the main riff is:

G-D-G-D#   G-D#-G-D

And obviously the Ds and D#s are higher pitched than the G (same G note every time). Only three notes, but have fun playing that for four minutes and eight seconds.