Hello,

I suggest to insert a VBA module with my UDF function UniqRandInt() (see
www.sulprobil.com),
then select cells A1:F1 enter
=UniqRandInt(40, false)
as array formula (CTRL+SHIFT+ENTER)
and copy this down to A10:F10.

I admire elegant worksheet function solutions, but if you like to have a
general and robust solution, a thoroughly tested UDF function might be the
answer of your choice (don't trust my function, test it!).

HTH,
Bernd