Calculating resistor for LEDs with different Forward Voltages in series

I need to work out what resistor I need for a series circuit containing 3 LEDs of 2 different types, and a 9v battery. I can do the maths, but I need to check I'm doing it right as I'm trying to learn this from what I can google!

LED1 V_F = 3.2V @ I_F = 20mA
LED2 V_F = 2.2V @ I_F = 20mA

Both LEDs have a Forward Current of 20mA at these Forward Voltages.

The circuit will contain 2x LED1 and 1x LED2.

So, using R = (V_S - V_F) / I_F, do I calculate the total V_F as 3.2V + 3.2V + 2.2V, therefore V_F = 8.6V?

Using the figures I have, I get:

(9 - 8.6) / (20 / 1000) = 20 ohm, so I'd need a 20Ω resistor?

Also, can anyone advise what type of resistor would be best?