I see. That is a nice change. The term m−1m−1 is always the same for every value m (except m = 1), as numerator and denominator are the same. So to get an integer number, the term m−12 must be an integer number itself. Very clever! that is to say whenever m−12 is an integer number, the whole sum is an integer number too, isn't it?
That's right. And the fraction can only be an integer when m−1≤2 i.e. m≤3
Right. My calculation confirmed that, as I have not found another values out which fits to the term. So from -1 to 3 all values (except 1, because its not definable) come into question.