936 B
936 B
id | challengeType | title |
---|---|---|
5900f5041000cf542c510016 | 5 | Problem 407: Idempotents |
Description
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.
Instructions
Tests
tests:
- text: <code>euler407()</code> should return 39782849136421.
testString: assert.strictEqual(euler407(), 39782849136421, '<code>euler407()</code> should return 39782849136421.');
Challenge Seed
function euler407() {
// Good luck!
return true;
}
euler407();
Solution
// solution required