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。