Let be a positive integer and let be the set of -tuples of strictly positive integers.
For and two elements of , we define:
- the Sum Of Products of and , denoted by , as the sum ;
- the Product Of Sums of and , denoted by , as the product .
Let be the sum of over all ordered pairs in such that .
For example: , , .
Find . Give your answer modulo .
Write-up coming later
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