freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-445-retractions-a.english.md

id, challengeType, title, forumTopicId

id	challengeType	title	forumTopicId
5900f52a1000cf542c51003c	5	Problem 445: Retractions A	302117

Description

For every integer n>1, the family of functions fn,a,b is defined by fn,a,b(x)≡ax+b mod n for a,b,x integer and 0You 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).

Find ∑ R(c) for c=C(10 000 000,k), and 1 ≤k≤ 9 999 999. Give your answer modulo 1 000 000 007.

Instructions

Tests

tests:
  - text: <code>euler445()</code> should return 659104042.
    testString: assert.strictEqual(euler445(), 659104042);

Challenge Seed

function euler445() {
  // Good luck!
  return true;
}

euler445();

Solution

// solution required