I know that it is correct to say
There is 1 composition of n.
but what if instead of "1", I use an expression that evaluates to 1? For example, what is the grammatical number in these sentences?
There is/are 20 composition(s) of n. (two to the zero)
There is/are 3 - 2 composition(s) of n. (three minus two)
There is/are 20=1 composition(s) of n. (two to the zero, which equals one)
There is/are 1=20 composition(s) of n. (one, which equals two to the zero)
This problem comes up somewhat frequently for me when describing the base case in a proof by induction.