ぃの计
计厩產稲焊疭 (Paul Erdos 1913-1996)
(酚The MacTutor History of Mathematics Achievehttp://www-gap.dcs.st-and.ac.uk/~history/ )
и s(x) ボ计 x 痷羆㎝ (Sum of Aliquot Divisors) рぃ珹┮Τ癬ㄓ
┏硂 s(x) 氮穦琌ぐ或计㎡穦ぃ穦Τㄇ俱计 n ㄏ s(x)=n 礚秆㎡
计厩產稲焊疭 (Paul Erdos 1913-1996) 靡礚计 n ㄏ s(x)=n 礚秆и嘿硂ㄇ计ぃの计 (Untouchable Number) 1000 ぃの计
2 5 52 88 96 120 124 146 162 188 206 210 216 246 248 262 268 276 288 290 292 304 322 324 326 342 372 406 408 426 430 448 472 474 498 516 518 520 530 540 552 556 562 576 584 612 624 626 628 658 668 670 714 718 726 732 738 748 750 756 766 768 782 784 792 802 804 818 836 848 852 872 892 894 896 898 902 916 926 936 964 966 976 982 996 ...
(OEIS A005114)
璝紈ぺ划瞦稱 (Goldbach Conjecture) 琌タ絋杠 5 獽琌暴ぃの计 (Odd Untouchable Number)硂妓┮Τぃ 6 案计糶Θㄢ计㎝玥ヴぃぶ 7 计だ╊Θㄢ计㎝ 1 2n+1 = p+q+1иσ納俱计 pqs(pq) = p+q+1 = 2n+1硂縒ミ靡㎡
и临祇瞷ㄇパぃの计舱Θ衡砃计 (Arithmetic Sequence)322 324 326 ㎝ 916 926 936单穦ヴ衡砃计㎡ぃの计丁回┏穦Τ㎡
计厩產临祇瞷ぃの计だ薄猵
俱计 |
ぃの计计 |
10 |
2 |
100 |
5 |
1000 |
89 |
10000 |
1212 |
┏ぃの计计琌耎床籔
硂琌ゼ秆ぇ良痙產秨祇
把σゅ膍の呼
Guy, R. K. "Untouchable Numbers." ”B10 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 66-67, 1994.
Weisstein, E. M. "Untouchable Number." From MathWorld. http://mathworld.wolfram.com/UntouchableNumber.html.
Wells, D. The Penguin Dictionary of Curious and Interesting Numbers. Middlesex, England: Penguin Books, p. 60, 1986.