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Extreme Palindromes

Kathy Q. Ji·Herbert S. Wilf
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Abstract

A recursively palindromic (RP) word is one that is a palindrome and whose left half-word and right half-word are each RP. Thus ABACABA is, and MADAM is not, an RP word. We count RP words of given length over a finite alphabet and RP compositions of an integer. We use the same method to determine the parity of the Catalan numbers.

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Kathy Q. Ji, Herbert S. Wilf. 2006-11-15. Extreme Palindromes. https://arxiv.org/abs/math/0611465

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