Denote the average of numbers by . Their variance is defined as .
Let be the sum of all quadruples of integers satisfying such that their average is exactly twice their variance.
For , there are such quadruples, namely: .
Hence . You are also given .
Find . Give your answer modulo .
对于 个数 ,记其平均数 ,方差为 。
记 为所有满足 ,且其平均数等于两倍的方差的整数四元组 的 之和。
时,共有 个符合要求的四元组。分别是:,故 。又已知 。
求 模 之值。
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