MAA-BIH ORG

Thirty-six 1×1x1 cubes are used to make a rectangular prism. How many different rectangular prisms can be made? If there’s a math formula in there, can you tell me what it is?

Considering only unique prisms and not rotations, there are eight.

1,1,36
1,2,18
1,3,12
1,4,9
1,6,6
2,2,9
2,3,6
3,3,4