Counting summations

It is possible to write five as a sum in exactly six different ways:

4 + 1 3 + 2 3 + 1 + 1 2 + 2 + 1 2 + 1 + 1 + 1 1 + 1 + 1 + 1 + 1

How many different ways can one hundred be written as a sum of at least two positive integers?

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