freeCodeCamp/problem-133-repunit-nonfactors.english.md at 22afc2a0ca354a1eb11919c51058918d7e953e22

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mrugesh 22afc2a0ca feat(learn): python certification projects (#38216 )

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Kristofer Koishigawa <scissorsneedfoodtoo@gmail.com>
Co-authored-by: Beau Carnes <beaucarnes@gmail.com>

2020-05-27 13:19:08 +05:30

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id, challengeType, isHidden, title, forumTopicId

id	challengeType	isHidden	title	forumTopicId
5900f3f21000cf542c50ff04	5	false	Problem 133: Repunit nonfactors	301761

Description

A number consisting entirely of ones is called a repunit. We shall define R(k) to be a repunit of length k; for example, R(6) = 111111. Let us consider repunits of the form R(10n). Although R(10), R(100), or R(1000) are not divisible by 17, R(10000) is divisible by 17. Yet there is no value of n for which R(10n) will divide by 19. In fact, it is remarkable that 11, 17, 41, and 73 are the only four primes below one-hundred that can be a factor of R(10n). Find the sum of all the primes below one-hundred thousand that will never be a factor of R(10n).

Instructions

Tests

tests:
  - text: <code>euler133()</code> should return 453647705.
    testString: assert.strictEqual(euler133(), 453647705);

Challenge Seed

function euler133() {
  // Good luck!
  return true;
}

euler133();

Solution

// solution required

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