Use inclusion-exclusion to find the number of ways to arrange the six numbers 1, 2, 3, 4, 5, 6 such that(adsbygoogle = window.adsbygoogle || []).push({});

either 1 is immediately followed by 2, or 3 is immediately followed by 4, or 5 is immediately followed

by 6.

I believe that this can be solved using unions. By setting the sets to be the numbers, the union should give two numbers next to each other. For example, set A1 as 1 and A2 as 2, then the union would be the number 1,2. However, wouldn't this union also be 2,1?

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# Inclusion-Exclusion principle problem

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