I had somebody ask about this. I was able to come up with 17 including a few which only had pilots that aired in black & white.

Andy Griffith.

Beverly Hillbillies

Bewitched
Beverly Hillbillies
Gilligan's Island
I Dream of Jeannie
Get Smart (only the pilot was B/W)
Petticoat Junction (?)

... and I'm not sure, but I think F Troop, also

The Joey Bishop Show went from B&W to Color and back to B&W.

The Lucy Show.

"The Andy Griffith show"
"The Beverly Hillbillies"
"Get Smart"
"The Lucy show"
"I Dream of Jeannie"
"Bewitched"
"F Troop"
"Hogans Heroes"
"The Adventures of Ozzie and Harriet"
"Gunsmoke"
"The Fugitive"

[list=1]
"Combat"
"Gomer Pyle-U.S.M.C."

Each show is listed under the season in which they first went into color.

The 1962-63 Season
1. The Flintstones (Seasons 3-6)
2. The Joey Bishop Show (Seasons 2-3) Season 4 went back to B&W
3. Hazel (Seasons 2-5)

The 1965-66 Season
4. The Adventures of Ozzie and Harriet (Season 14)
5. My Three Sons (Seasons 6-12)
6. The Andy Griffith Show (Seasons 6-8)
7. The Beverly Hillbillies (Seasons 4-9)
8. The Lucy Show (Seasons 4-6)
9. The Farmer's Daughter (Season 3)
10. Petticoat Junction (Seasons 3-7)
11. My Favorite Martian (Season 3)
12. Gomer Pyle, U.S.M.C. (Seasons 2-5)
13. Gilligan's Island (Seasons 2-3)
14. Please Don't Eat the Daisies (Pilot B&W, Series in Color)
15. Hogan's Heroes (Pilot B&W, Series in Color)
16. Get Smart (Pilot B&W, Series in Color)

The 1966-67 Season
17. Bewitched (Seasons 3-8)
18. I Dream of Jeannie (Seasons 2-5)