If you were going C, Am, F and G. (1, 6m, 4, 5)
Then the beginning of the rainbow song,
C, Am, Dm, and G7 is virtually the same.
Dm is the relative minor for F. So it clicks right into the formula.
The second line, Cmaj7, Am, Dm and G7 is still about the same. Just a variation. You play a fancy C chord.
I play this version:
Intro: C Cmaj7 Am F C G Am F Fadd9 F
C Em F C
Oooo, oooo, oooo...
F E7 Am F
Oooo, oooo, oooo...
C Em
Somewhere over the rainbow
F C
- Way up high
F C
And the dreams that you dream of
G Am F
Once in a lullaby...
- C Em
Oh, somewhere over the rainbow
F C
- Blue birds fly
F C
And the dreams that you dream of
G Am F
Dreams really do come true...