but I don't know how I'm supposed to integrate the voltage drop of the LEDs into the equations:
(Add, not subtract because the equations use electron flow so everything is backwards.)
If you look at the circuit in reply 7 you will see that the resistor connected to pin 5 has the current from two lots of LEDs through it. All the other sets of diodes only have resistors with one lot of LEDs going through them. This means that this resistor drops more voltage than the others and so reduces the current through those LEDs.