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614. 特殊分拆2
题目 Problem 614: Special partitions 2 An integer partition of a number n is a way of writing n as a sum of positive integers. Partitions …...
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618. 素因子和固定的数
题目 Problem 618: Numbers with a given prime factor sum Consider the numbers 15, 16 and 18: 15 = 3×5 and 3+5 = 8. 16 = 2×2×2×2 and 2+2+2+2…...
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615. 第一百万个拥有至少一百万个素因数的数
题目 Problem 615. The millionth number with at least one million prime factors Consider the natural numbers having at least 5 prime factor…...
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617. 镜像幂序列
题目 Problem 617. Mirror Power Sequence For two integers n, e > 1, we define a(n,e)-MPS (Mirror Power Sequence) to be an infinite seque…...
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616. 有创造力的数
题目 Problem 616: Creative numbers Alice plays the following game, she starts with a list of integers L and on each step she can either: …...
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613. 毕达哥拉斯的蚂蚁
题目 Problem 613. Pythagorean Ant Dave is doing his homework on the balkony and, prepairing a presentation about Pythogorean triangles, ha…...
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612. 朋友数
题目 Problem 612. Friend numbers Let's call two numbers friend numbers if their representation in base 10 has at least one common digi…...
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579. 格点立方体上的格点
题目 Problem 579. Lattice points in lattice cubes A lattice cube is a cube in which all vertices have integer coordinates. Let C(n) be the…...
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610. 罗马数字(II)
题目 Prolem 610. Roman Numerals II A random generator produces a sequence of symbols drawn from the set {I, V, X, L, C, D, M, #}. Each ite…...
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089. 罗马数字
题目 Problem 89. Roman numerals For a number written in Roman numerals to be considered valid there are basic rules which must be followed…...
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609. π 序列
题目 Problem 609. π sequences For every n ≥ 1 the prime-counting function π(n) is equal to the number of primes not exceeding n. E.g. π(6)…...
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591. 二次整数最佳逼近
题目 Problem 591: Best Approximations by Quadratic Integers Given a non-square integer d, any real x can be approximated arbitrarily close…...