A New Record for 1324-avoiding Permutations
نویسندگان
چکیده
We prove that the class of 1324-avoiding permutations has exponential growth rate at most 13.74. To Richard Stanley, on the occasion of his seventieth birthday.
منابع مشابه
Counting 1324-Avoiding Permutations
We consider permutations that avoid the pattern 1324. By studying the generating tree for such permutations, we obtain a recurrence formula for their number. A computer program provides data for the number of 1324-avoiding permutations of length up to 20.
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We give an improved algorithm for counting the number of 1324-avoiding permutations, resulting in 5 further terms of the generating function. We analyse the known coefficients and find compelling evidence that unlike other classical length-4 patternavoiding permutations, the generating function in this case does not have an algebraic singularity. Rather, the number of 1324-avoiding permutations...
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