A clock sequence is a periodic sequence of positive integers that can be broken into contiguous segments such that the sum of the $n$-th segment is equal to $n$.
For example, the sequence $$1\ 2\ 3\ 4\ 3\ 2\ 1\ 2\ 3\ 4\ 3\ 2\ 1\ 2\ 3\ 4\ 3\ 2\ 1\ \cdots$$ is a clock sequence with period $6$, as it can be broken into $$1\Big |2\Big |3\Big |4\Big |3\ 2\Big |1\ 2\ 3\Big |4\ 3\Big |2\ 1\ 2\ 3\Big |4\ 3\ 2\Big |1\ 2\ 3\ 4\Big |3\ 2\ 1\ 2\ 3\Big |\cdots$$ Let $C(N)$ be the number of different clock sequences with period at most $N$. For example, $C(3) = 3$, $C(4) = 7$ and $C(10) = 561$.
Find $C(10^4) \bmod 1111211113$.
Solution
No solution yet. Write yours at
solutions/s908.md.