747 B
747 B
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5900f4ea1000cf542c50fffc | Problem 381: (prime-k) factorial | 5 | 302045 | problem-381-prime-k-factorial |
--description--
For a prime p let S(p) = (∑(p-k)!) mod(p) for 1 ≤ k ≤ 5.
For example, if p=7, (7-1)! + (7-2)! + (7-3)! + (7-4)! + (7-5)! = 6! + 5! + 4! + 3! + 2! = 720+120+24+6+2 = 872. As 872 mod(7) = 4, S(7) = 4.
It can be verified that ∑S(p) = 480 for 5 ≤ p < 100.
Find ∑S(p) for 5 ≤ p < 108.
--hints--
euler381()
should return 139602943319822.
assert.strictEqual(euler381(), 139602943319822);
--seed--
--seed-contents--
function euler381() {
return true;
}
euler381();
--solutions--
// solution required