45 lines
783 B
Markdown
45 lines
783 B
Markdown
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---
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id: 5900f52a1000cf542c51003c
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title: 'Problem 445: Retractions A'
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challengeType: 5
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forumTopicId: 302117
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dashedName: problem-445-retractions-a
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---
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# --description--
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For every integer n>1, the family of functions fn,a,b is defined
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by fn,a,b(x)≡ax+b mod n for a,b,x integer and 0
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You are given that ∑ R(c) for c=C(100 000,k), and 1 ≤ k ≤99 999 ≡628701600 (mod 1 000 000 007). (C(n,k) is the binomial coefficient).
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Find ∑ R(c) for c=C(10 000 000,k), and 1 ≤k≤ 9 999 999. Give your answer modulo 1 000 000 007.
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# --hints--
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`euler445()` should return 659104042.
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```js
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assert.strictEqual(euler445(), 659104042);
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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 euler445() {
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return true;
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}
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euler445();
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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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