freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-441-the-inverse-summation-of-coprime-couples.md

id, title, challengeType, forumTopicId, dashedName

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

--description--

For an integer M, we define R(M) as the sum of \frac{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) = \frac{1}{2}, S(10) ≈ 6.9147 and S(100) ≈ 58.2962.

Find S({10}^7). Give your answer rounded to four decimal places.

--hints--

inverseSummationCoprimeCouples() should return 5000088.8395.

assert.strictEqual(inverseSummationCoprimeCouples(), 5000088.8395);

--seed--

--seed-contents--

function inverseSummationCoprimeCouples() {

  return true;
}

inverseSummationCoprimeCouples();

--solutions--

// solution required