freeCodeCamp/curriculum/challenges/en/08-coding-interview-prep/project-euler/problem-258-a-lagged-fibonacci-sequence.en.md

id, challengeType, title

id	challengeType	title
5900f46e1000cf542c50ff81	5	Problem 258: A lagged Fibonacci sequence

Description

A sequence is defined as:

gk = 1, for 0 ≤ k ≤ 1999 gk = gk-2000 + gk-1999, for k ≥ 2000. Find gk mod 20092010 for k = 1018.

Instructions

Tests

- text: <code>euler258()</code> should return 12747994.
  testString: 'assert.strictEqual(euler258(), 12747994, ''<code>euler258()</code> should return 12747994.'');'

Challenge Seed

function euler258() {
  // Good luck!
  return true;
}

euler258();

Solution

// solution required