Alberto,

An excerpt from your message:

In my opinion it contained an error, as it used the same
formula involving AL, both with ferrite toroids and
iron-powder toroids. Amidon gives two different
formulas for the two cases. I corrected it, and added
a couple of other, maybe useful, functions.

I think you'll find that each Amidon formula is "different" by scaling
factor only.  Inductance is still "turns squared" and scaling coefficients
and turn reference numbers are selected to arrive at convenient values in
millihenries for ferrites (generally high Al values) and microhenries for
powdered iron (generally low Al values).

73, Bob ZL2CA