Im trying to find a general formula I can store in my calculator that can find the number of onto (surjective) functions exists for a relation of when M is mapped to N.(adsbygoogle = window.adsbygoogle || []).push({});

I can't seem to find a nice formula for it, but based on the below material I will show you what I have developed.

From: Discrete Mathemeatics and Its Applications 7th Edition Rosen pg. 561

From: Discrete Mathemeatics and Its Applications 7th Edition Rosen pg. 512

Random Chegg Problem from Google Search I'm using to verify with:

Here is what I've formed, written out:

In the TI nSpire CX CAS, it's written like this:

And as you can see, the chegg problem I'm trying to verify it with doesn't match!

But I think it should! If I manually iterate the function like so:

The values are correct and what Chegg is showing. What have I done wrong in my equation?

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# What is wrong with my summation formula?

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