freeCodeCamp

id	challengeType	title	forumTopicId
5900f5261000cf542c510038	5	Problem 441: The inverse summation of coprime couples	302113

Description

For an integer M, we define R(M) as the sum of 1/(p·q) for all the integer pairs p and q which satisfy all of these conditions:

1 ≤ p < q ≤ M p + q ≥ M p and q are coprime.

We also define S(N) as the sum of R(i) for 2 ≤ i ≤ N. We can verify that S(2) = R(2) = 1/2, S(10) ≈ 6.9147 and S(100) ≈ 58.2962.

Find S(107). Give your answer rounded to four decimal places.

tests:
  - text: <code>euler441()</code> should return 5000088.8395.
    testString: assert.strictEqual(euler441(), 5000088.8395);

function euler441() {
  // Good luck!
  return true;
}

euler441();

// solution required