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In mathematics, the Golomb–Dickman constant arises in the theory of random permutations and in number theory. Its value is : Let ''a''''n'' be the average — taken over all permutations of a set of size ''n'' — of the length of the longest cycle in each permutation. Then the Golomb–Dickman constant is : In the language of probability theory, is asymptotically the expected length of the longest cycle in a uniformly distributed random permutation of a set of size ''n''. In number theory, the Golomb–Dickman constant appears in connection with the average size of the largest prime factor of an integer. More precisely, : where is the largest prime factor of ''k''. So if ''k'' is a ''d'' digit integer, then is the asymptotic average number of digits of the largest prime factor of ''k''. The Golomb–Dickman constant appears in number theory in a different way. What is the probability that second largest prime factor of ''n'' is smaller than the square root of the largest prime factor of ''n''? Asymptotically, this probability is . More precisely, : where is the second largest prime factor ''n''. There are several expressions for . Namely, : where is the exponential integral, : and : where is the Dickman function. == See also == * Random permutation * Random permutation statistics 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Golomb–Dickman constant」の詳細全文を読む スポンサード リンク
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