43 lines
683 B
Markdown
43 lines
683 B
Markdown
---
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id: 5900f3e41000cf542c50fef7
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title: 'Problem 120: Square remainders'
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challengeType: 5
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forumTopicId: 301747
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dashedName: problem-120-square-remainders
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---
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# --description--
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Let r be the remainder when (a−1)n + (a+1)n is divided by a2.
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For example, if a = 7 and n = 3, then r = 42: 63 + 83 = 728 ≡ 42 mod 49. And as n varies, so too will r, but for a = 7 it turns out that rmax = 42.
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For 3 ≤ a ≤ 1000, find ∑ rmax.
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# --hints--
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`euler120()` should return 333082500.
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```js
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assert.strictEqual(euler120(), 333082500);
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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 euler120() {
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return true;
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}
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euler120();
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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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