45 lines
867 B
Markdown
45 lines
867 B
Markdown
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---
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id: 5900f5261000cf542c510038
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title: 'Problem 441: The inverse summation of coprime couples'
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challengeType: 5
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forumTopicId: 302113
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dashedName: problem-441-the-inverse-summation-of-coprime-couples
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---
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# --description--
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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:
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1 ≤ p < q ≤ M p + q ≥ M p and q are coprime.
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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.
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Find S(107). Give your answer rounded to four decimal places.
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# --hints--
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`euler441()` should return 5000088.8395.
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```js
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assert.strictEqual(euler441(), 5000088.8395);
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```
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# --seed--
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## --seed-contents--
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```js
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function euler441() {
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return true;
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}
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euler441();
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```
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# --solutions--
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```js
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// solution required
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```
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