Being : R= Radius, G= Gravity force, V= Speed, a= Bank Angle,n= Load Factor.
1:R=V*V/(G*Tan(a))
2:n=1/cos(a)
from 1 we find that:
R/(V*V)=1/Tan(a)
Tan(a)=V*V/R
a=Tan -1 (V*V/R)
thus
n= 1/(cos(Tan-1 (V*V/R)))
ps: Watch out ! use the correct units of measure.