# Number of $$1$$s in Compositions of $$20$$

A composition of a positive integer $$n$$ is an expression of $$n$$ as the sum of only 1s and 2s, where the order matters.

For example, $$(1+1+1)$$, $$(1+2)$$, and $$(2+1)$$ are all possible compositions of 3.
The number of total 1s in all three of these compositions is 5.

Find the total number of 1s in all possible compositions of 20.

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