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This article mainly introduces how to achieve java is not the sum of surplus, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor with you to understand.

Perfect numbers are those whose sum of true factors is equal to themselves. For example, the sum of the true factors of 28 is 1 + 2 + 4 + 7 + 14 = 28, so 28 is a complete number.

A number n is called a deficiency if the sum of its true factors is less than n; otherwise, it is called a surplus.

Since 12 is the minimum surplus number, the sum of its true factor is 1 + 2 + 3 + 4 + 6 = 16, so the smallest number that can be expressed as the sum of two surplus numbers is 24. Through mathematical analysis, it can be concluded that all numbers greater than 28123 can be written as the sum of two surplus numbers; although we know that the largest number that cannot be written as the sum of two surplus numbers is less than this value, but this is the best upper bound that can be obtained through analysis.

Find out all the positive integers that cannot be written as the sum of two surplus numbers and find their sum.

System.out.println (smallestMultiple (20))

Analysis:

In fact, it is to find the minimum common multiple from 1 to 20, and the minimum common multiple from 1 to n is also a multiple of n * (nMU1). It is judged by constantly multiplying the multiple of n * (nMel 1). If 1 to n is divisible by him, it will be returned directly.

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