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In analytic number theory, the Dickman function or Dickman–de Bruijn function ρ is a special function used to estimate the proportion of smooth numbers up to a given bound. It was first studied by actuary Karl Dickman, who defined it in his only mathematical publication, and later studied by the Dutch mathematician Nicolaas Govert de Bruijn. ==Definition== The Dickman-de Bruijn function is a continuous function that satisfies the delay differential equation : with initial conditions for 0 ≤ ''u'' ≤ 1. Dickman proved that, when is fixed, we have : where is the number of ''y''-smooth (or ''y''-friable) integers below ''x''. Ramaswami later gave a rigorous proof that for fixed ''a'', was asymptotic to , with the error bound : in big O notation. 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「Dickman function」の詳細全文を読む スポンサード リンク
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