1018 B

Raw Blame History

id	title	challengeType	forumTopicId	dashedName
5900f5181000cf542c51002a	Problem 427: n-sequences	5	302097	problem-427-n-sequences

--description--

A sequence of integers S = {si} is called an n-sequence if it has n elements and each element si satisfies 1 ≤ si ≤ n. Thus there are nn distinct n-sequences in total.

For example, the sequence S = {1, 5, 5, 10, 7, 7, 7, 2, 3, 7} is a 10-sequence.

For any sequence S, let L(S) be the length of the longest contiguous subsequence of S with the same value. For example, for the given sequence S above, L(S) = 3, because of the three consecutive 7's.

Let f(n) = ∑ L(S) for all n-sequences S.

For example, f(3) = 45, f(7) = 1403689 and f(11) = 481496895121.

Find f(7 500 000) mod 1 000 000 009.

--hints--

euler427() should return 97138867.

assert.strictEqual(euler427(), 97138867);

--seed--

--seed-contents--

function euler427() {

  return true;
}

euler427();

--solutions--

// solution required

1018 B Raw Blame History