The number of permutations with a given number of sequences
نویسنده
چکیده
P (n, s) denotes the number of permutations of 1, 2,. .. n that have exactly s sequences. Canfield and Wilf [math.CO/0609704] recently showed that P (n, s) can be written as a sum of s polynomials in n. We determine these polynomials explicitly and also obtain explicit expressions for P (n, s) and its fixed-s generating function us(x).
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تاریخ انتشار 2006