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Problem 123


Problem 123


Prime square remainders

Let pn be the nth prime: 2, 3, 5, 7, 11, …, and let r be the remainder when (pn?1)n + (pn+1)n is divided by pn2.

For example, when n = 3, p3 = 5, and 43 + 63 = 280 ≡ 5 mod 25.

The least value of n for which the remainder first exceeds 109 is 7037.

Find the least value of n for which the remainder first exceeds 1010.


素数平方余数

记pn是第n个素数:2、3、5、7、11……;记r是(pn?1)n + (pn+1)n被pn2除所得的余数。

例如,当n = 3时,p3 = 5,而43 + 63 = 280 ≡ 5 mod 25。

使余数首次超过109的最小n值是7037。

求使余数首次超过1010的最小n值。