"Peter T" wrote:
Now if you can derive some formula that returns 16431
for the filtered '4 out of 6' that would validate my routine!

I have tried to count this in the past, and I believe I never succeeded.

That is why I would like to see your 16,431 combinations.

My algorithm generated 2240; and I do not see any mistake (yet). I posted a
pointer to my uploaded file in another response.