633 B
633 B
id | title | challengeType | forumTopicId |
---|---|---|---|
5900f5041000cf542c510016 | Problem 407: Idempotents | 5 | 302075 |
--description--
If we calculate a2 mod 6 for 0 ≤ a ≤ 5 we get: 0,1,4,3,4,1.
The largest value of a such that a2 ≡ a mod 6 is 4. Let's call M(n) the largest value of a < n such that a2 ≡ a (mod n). So M(6) = 4.
Find ∑M(n) for 1 ≤ n ≤ 107.
--hints--
euler407()
should return 39782849136421.
assert.strictEqual(euler407(), 39782849136421);
--seed--
--seed-contents--
function euler407() {
return true;
}
euler407();
--solutions--
// solution required