55 lines
1.3 KiB
Markdown
55 lines
1.3 KiB
Markdown
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---
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id: 5900f4741000cf542c50ff86
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title: 'Problem 263: An engineers'' dream come true'
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challengeType: 5
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forumTopicId: 301912
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dashedName: problem-263-an-engineers-dream-come-true
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---
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# --description--
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Consider the number 6. The divisors of 6 are: 1,2,3 and 6.
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Every number from 1 up to and including 6 can be written as a sum of distinct divisors of 6:
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1=1, 2=2, 3=1+2, 4=1+3, 5=2+3, 6=6.
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A number n is called a practical number if every number from 1 up to and including n can be expressed as a sum of distinct divisors of n.
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A pair of consecutive prime numbers with a difference of six is called a sexy pair (since "sex" is the Latin word for "six"). The first sexy pair is (23, 29).
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We may occasionally find a triple-pair, which means three consecutive sexy prime pairs, such that the second member of each pair is the first member of the next pair.
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We shall call a number n such that : (n-9, n-3), (n-3,n+3), (n+3, n+9) form a triple-pair, and the numbers n-8, n-4, n, n+4 and n+8 are all practical,
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an engineers’ paradise.
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Find the sum of the first four engineers’ paradises.
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# --hints--
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`euler263()` should return 2039506520.
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```js
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assert.strictEqual(euler263(), 2039506520);
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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 euler263() {
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return true;
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}
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euler263();
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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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