yaworsw/euler-manager

---
:id: 381
:name: "(prime-k) factorial"
:url: https://projecteuler.net/problem=381
:content: "For a prime p let S(p) = (∑(p-k)!) mod(p) for 1 ≤ k ≤ 5.\n\nFor example,
  if p=7,  \n(7-1)! + (7-2)! + (7-3)! + (7-4)! + (7-5)! = 6! + 5! + 4! + 3! + 2! =
  720+120+24+6+2 = 872.  \n As 872 mod(7) = 4, S(7) = 4.\n\nIt can be verified that
  ∑S(p) = 480 for 5 ≤ p \\< 100.\n\nFind ∑S(p) for 5 ≤ p \\< 10<sup>8</sup>.\n\n"