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In mathematics, a divisibility sequence is an integer sequence such that for all natural numbers ''m'', ''n'', : i.e., whenever one index is a multiple of another one, then the corresponding term also is a multiple of the other term. The concept can be generalized to sequences with values in any ring where the concept of divisibility is defined. A strong divisibility sequence is an integer sequence such that for all natural numbers ''m'', ''n'', : Note that a strong divisibility sequence is immediately a divisibility sequence; if , immediately . Then by the strong divisibility property, and therefore . ==Examples== * Any constant sequence is a strong divisibility sequence. * Every sequence of the form , for some nonzero integer ''k'', is a divisibility sequence. * Every sequence of the form for integers is a divisibility sequence. * The Fibonacci numbers ''F'' = (1, 1, 2, 3, 5, 8,...) form a strong divisibility sequence. * More generally, Lucas sequences of the first kind are divisibility sequences. * Elliptic divisibility sequences are another class of such sequences. 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「Divisibility sequence」の詳細全文を読む スポンサード リンク
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