Problem with Buckling of stepped bar Roark's Formula's

RaymondSE

Hello,

I have a problem with calculating buckling on a stepped bar with roark's formulas for stress and strain.

By these tables (page 718-722) they show tables where you can find K1 values to calculate the maximum buckling load.
In these tables you compare:
-(E2I2/E1I1) E is youngs modulus and I is moment of inertia.
-A/L The ratio of length of upper and lower part.
-The ratio between P1 and P2

In my case:
P2 = 0.
A/L = 0.65
But E2I2/E1I1 = 3.36

This value is not tabulated.
Does anyone know how can I find K1 for this value.

Raymond