Files

gikf 67de105117 fix(curriculum): clean-up Project Euler 241-260 (#42879 )

* fix: clean-up Project Euler 241-260

* fix: typo

* Update curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-255-rounded-square-roots.md

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

2021-07-16 12:21:45 +02:00

1.0 KiB

Raw Blame History

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
5900f4621000cf542c50ff74	Problem 245: Coresilience	5	301892	problem-245-coresilience

--description--

We shall call a fraction that cannot be cancelled down a resilient fraction.

Furthermore we shall define the resilience of a denominator, R(d), to be the ratio of its proper fractions that are resilient; for example, R(12) = \frac{4}{11}.

The resilience of a number d > 1 is then \frac{φ(d)}{d − 1} , where φ is Euler's totient function.

We further define the coresilience of a number n > 1 as C(n) = \frac{n − φ(n)}{n − 1}.

The coresilience of a prime p is C(p) = \frac{1}{p − 1}.

Find the sum of all composite integers 1 < n ≤ 2 × {10}^{11}, for which C(n) is a unit fraction.

--hints--

coresilience() should return 288084712410001.

assert.strictEqual(coresilience(), 288084712410001);

--seed--

--seed-contents--

function coresilience() {

  return true;
}

coresilience();

--solutions--

// solution required

1.0 KiB Raw Blame History Unescape Escape