76 lines
1022 B
Markdown
76 lines
1022 B
Markdown
---
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id: 5900f4e61000cf542c50fff9
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challengeType: 5
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title: 'Problem 378: Triangle Triples'
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forumTopicId: 302040
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---
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## Description
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<section id='description'>
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Let T(n) be the nth triangle number, so T(n) =
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n (n+1)2
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.
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Let dT(n) be the number of divisors of T(n).
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E.g.:
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T(7) = 28 and dT(7) = 6.
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Let Tr(n) be the number of triples (i, j, k) such that 1 ≤ i < j < k ≤ n and dT(i) > dT(j) > dT(k).
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Tr(20) = 14, Tr(100) = 5772 and Tr(1000) = 11174776.
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Find Tr(60 000 000).
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Give the last 18 digits of your answer.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>euler378()</code> should return 147534623725724700.
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testString: assert.strictEqual(euler378(), 147534623725724700);
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function euler378() {
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return true;
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}
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euler378();
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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