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In mathematics, a nonhypotenuse number is a natural number whose square ''cannot'' be written as the sum of two nonzero squares. The name stems from the fact that an edge of length equal to a nonhypotenuse number ''cannot'' form the hypotenuse of a right angle triangle with integer sides. The numbers 1, 2, 3 and 4 are all nonhypotenuse numbers. The number 5, however, is ''not'' a nonhypotenuse number as 52 equals 32 + 42. The first fifty nonhypotenuse numbers are: :1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 14, 16, 18, 19, 21, 22, 23, 24, 27, 28, 31, 32, 33, 36, 38, 42, 43, 44, 46, 47, 48, 49, 54, 56, 57, 59, 62, 63, 64, 66, 67, 69, 71, 72, 76, 77, 79, 81, 83, 84 Although nonhypotenuse numbers are common among small integers, they become more-and-more sparse for larger numbers. Yet, there are infinitely many nonhypotenuse numbers, and the number of nonhypotenuse numbers not exceeding a value x scales asymptotically with x/√(log x).〔. This review of a manuscript of Beiler's (which was later published in ''J. Rec. Math.'' 7 (1974) 120–133, ) attributes this bound to Landau.〕 The nonhypotenuse numbers are those numbers that have no prime factors of the form 4k+1.〔.〕 Equivalently, any number that cannot be put into the form where K, m, and n are all positive integers, is never a nonhypotenuse number. A number whose prime factors are not ''all'' of the form 4k+1 cannot be the hypotenuse of a primitive triangle, but may still be the hypotenuse of a non-primitive triangle. ==See also== *Nonhypotenuse Numbers *Eta Numbers *Pythagorean theorem *Landau-Ramanujan constant *Fermat's theorem on sums of two squares 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「Nonhypotenuse number」の詳細全文を読む スポンサード リンク
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