Numbers n such that n divides 2^n + 1.(Formerly M2806)Select[Range[10^5], Divisible[2^# + 1, #] &] (* 注：效率不如 PowerMod. *)} 除了形如3^k, 还有其他的解：形如 a*3^k的，除了a=1， 还有a=19*9=171，a=3249=19^2*9，a=13203=163*9*9，... 待研究。Select[1 + ...
5. Does there exist a positive integer n such that n has exactly 2000 prime divisors and n divides 2"+1?(RUS)5.确定是否存在满足下列条件的正整数n:n恰好能够被2000个互不相同的质数整除,且 2^n+1 能够被n整除.(俄罗斯) 相关知识点:
1. Let n be a positive integer and let a,., a_k(k≥2) be distinct integers in the set (1,⋯,n)such that n divides a, (a,+1-1) for i =1,…, k-1. Prove that n does not divide a_k(a_1-1)(AUS)1.设n是一个正整数,a1, a_2 ,…, a_k(k≥2) 是集合 (1,...
取分母n-1,可使样本方差的期望等于总体方差,即这种定义的样本方差是总体方差的无偏估计。 简单理解,因为算方差用到了均值,所以自由度就少了1,自然就是除以(n-1)了。 再不能理解的话,形象一点,对于样本方差来说,假如从总体中只取一个样本,即n=1,那么样本方差公式的分子分母都为0,方差完全不确定。这个好理解...
设a1a2……an是任意正整数,证明:存在i在k(i>=0,k>=1)使得ai+1 + ai+2 +……+ai+k能被n整除 试证明:4^k-1一定能被3整除,其中k为正整数. 证明所有k,n属于整数,(k-n)能被(k-1)整除当且仅当(k-n)能被(n-1)整除.英文原题:For all k,n in Z,(k-n) divides (k-1) if only if ...
(define (inc x) (1+ x))(define (square x) (* x x))(define (pnext n)(if (= n 2)3 (+ n 2)))(define (divides? a b)(= (remainder b a) 0))(define (test n testdivisor)(cond ((> (square testdivisor) n) n)((divides? testdivisor n) testdivisor)(else (...
故答案为B。 (2)C.考查动词及语境理解。 A.knew知道; B .learned学习 ; C .noticed注意到; D. acknow ledged承认。 根据下文I have a line of apple tre es running alongside the fence可知,作者觉得 他邻居应该注意到了沿着篱笆有一排苹果树。 故答 案为C。 (3)C.考查动词及语境理解。 A ....
表示坏处 1) It has more disadvantages than advantages. 2) It does us much harm. 3) It is harmful to us. 例如:However, everything divides into two. Television can also be harmful to us. It can do harm to our health and make us lazy if we spend too much time watching television.反...
Adds 1 CR 1- ( nu1 -- nu2 ) Subtracts 1 CR 2+ ( nu1 -- nu2 ) Adds 2 CR 2- ( nu1 -- nu2 ) Subtracts 2 59 2* ( x1 -- x2 ) Multiplies by 2 57 2/ ( x1 -- x2 ) Divides by 2 27 lshift ( x1 u -- x2 ) Left shifts x1 ...
Improvement has been made in the following two parts: the first one issegmentation dictionary, which divides the singular one into the basic one and the characteristic word one. 首先是在分词词典方面,将以往单一的词典分为基本词典和特征词词典两个部分。