1.2 KiB
1.2 KiB
id | challengeType | title | forumTopicId |
---|---|---|---|
5900f5241000cf542c510037 | 5 | Problem 440: GCD and Tiling | 302112 |
Description
For example, here are some of the ways to tile a board of length n = 8:
Let T(n) be the number of ways to tile a board of length n as described above.
For example, T(1) = 10 and T(2) = 101.
Let S(L) be the triple sum ∑a,b,c gcd(T(ca), T(cb)) for 1 ≤ a, b, c ≤ L. For example: S(2) = 10444 S(3) = 1292115238446807016106539989 S(4) mod 987 898 789 = 670616280.
Find S(2000) mod 987 898 789.
Instructions
Tests
tests:
- text: <code>euler440()</code> should return 970746056.
testString: assert.strictEqual(euler440(), 970746056);
Challenge Seed
function euler440() {
return true;
}
euler440();
Solution
// solution required