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* fix: remove isHidden flag from frontmatter * fix: add isUpcomingChange Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com> * feat: hide blocks not challenges Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com> Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com>
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id, challengeType, title, forumTopicId
| id | challengeType | title | forumTopicId |
|---|---|---|---|
| 5900f3b21000cf542c50fec5 | 5 | Problem 70: Totient permutation | 302183 |
Description
Euler's Totient function, φ(n) [sometimes called the phi function], is used to determine the number of positive numbers less than or equal to n which are relatively prime to n. For example, as 1, 2, 4, 5, 7, and 8, are all less than nine and relatively prime to nine, φ(9)=6. The number 1 is considered to be relatively prime to every positive number, so φ(1)=1.
Interestingly, φ(87109)=79180, and it can be seen that 87109 is a permutation of 79180.
Find the value of n, 1 < n < 107, for which φ(n) is a permutation of n and the ratio n/φ(n) produces a minimum.
Instructions
Tests
tests:
- text: <code>totientPermutation()</code> should return a number.
testString: assert(typeof totientPermutation() === 'number');
- text: <code>totientPermutation()</code> should return 8319823.
testString: assert.strictEqual(totientPermutation(), 8319823);
Challenge Seed
function totientPermutation() {
// Good luck!
return true;
}
totientPermutation();
Solution
// solution required