It's not the number of sets with at most 4 elements (which would be 1820), it's ...

		yorwba on Jan 28, 2018 \| parent \| context \| favorite \| on: Show HN: How to store a set of four 5-bit values i... It's not the number of sets with at most 4 elements (which would be 1820), it's the number of bags with exactly 4 elements (i.e. the multiplicity of duplicate elements matters). https://en.wikipedia.org/wiki/Bag_(mathematics)#Counting_mul...