47 lines
886 B
Markdown
47 lines
886 B
Markdown
---
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id: 5900f49d1000cf542c50ffb0
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title: 'Problem 305: Reflexive Position'
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challengeType: 5
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forumTopicId: 301959
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dashedName: problem-305-reflexive-position
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---
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# --description--
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Let's call S the (infinite) string that is made by concatenating the consecutive positive integers (starting from 1) written down in base 10.
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Thus, S = 1234567891011121314151617181920212223242...
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It's easy to see that any number will show up an infinite number of times in S.
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Let's call f(n) the starting position of the nth occurrence of n in S. For example, f(1)=1, f(5)=81, f(12)=271 and f(7780)=111111365.
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Find ∑f(3k) for 1≤k≤13.
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# --hints--
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`euler305()` should return 18174995535140.
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```js
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assert.strictEqual(euler305(), 18174995535140);
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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 euler305() {
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return true;
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}
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euler305();
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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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