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Problem 132


Problem 132


Large repunit factors

A number consisting entirely of ones is called a repunit. We shall define R(k) to be a repunit of length k.

For example, R(10) = 1111111111 = 11×41×271×9091, and the sum of these prime factors is 9414.

Find the sum of the first forty prime factors of R(109).


大循环单位数的因数

只包含数字1的数被称为循环单位数,我们定义R(k)是长为k的循环单位数。

例如,R(10) = 1111111111 = 11×41×271×9091,这些质因数的和是9414。

找出R(109)的前40个质因数的和。