How about this, everyone . . .. .  2 coils result in 1/2 the resistance.   3 coils result in 1/3 x Ω.  4 coils result in 1/4 x Ω.  (I'm starting to see a pattern there.)
There are no setups with coils in series, unless you're vaping two devices at once.  In series, each coil is an individual function, and has it's own resistance.