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In mathematics, a superior highly composite number is a natural number which has more divisors than any other number . It is a stronger restriction than that of a highly composite number, which is defined as having more divisors than any smaller positive integer. The first 10 superior highly composite numbers and their factorization are listed. For a superior highly composite number ''n'' there exists a positive real number ''ε'' such that for all natural numbers ''k'' smaller than ''n'' we have : and for all natural numbers ''k'' larger than ''n'' we have : where ''d(n)'', the divisor function, denotes the number of divisors of ''n''. The term was coined by Ramanujan (1915). The first 15 superior highly composite numbers, 2, 6, 12, 60, 120, 360, 2520, 5040, 55440, 720720, 1441440, 4324320, 21621600, 367567200, 6983776800 are also the first 15 colossally abundant numbers, which meet a similar condition based on the sum-of-divisors function rather than the number of divisors. == Properties == All superior highly composite numbers are highly composite. An effective construction of the set of all superior highly composite numbers is given by the following monotonic mapping from the positive real numbers.〔Ramanujan (1915); see also URL http://wwwhomes.uni-bielefeld.de/achim/hcn.dvi〕 Let : for any prime number ''p'' and positive real ''x''. Then : is a superior highly composite number. Note that the product need not be computed indefinitely, because if then , so the product to calculate can be terminated once . Also note that in the definition of , is analogous to in the implicit definition of a superior highly composite number. Moreover for each superior highly composite number exists a half-open interval such that . This representation implies that there exist an infinite sequence of such that for the ''n''-th superior highly composite number holds : The first are 2, 3, 2, 5, 2, 3, 7, ... . In other words, the quotient of two successive superior highly composite numbers is a prime number. 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「Superior highly composite number」の詳細全文を読む スポンサード リンク
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