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heyyolol's blog

By heyyolol, history, 2 months ago, In English,

Does anyone want to help explain the formula for counting number of permutations with no hits to the main diagonal: https://oeis.org/A003471 ? It was needed in one of my country's training contest yesterday, so I'm interested to find out more about how the formula is derived. Thank you!

 
 
 
 
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