
Sequences with Nice Divisibility Properties
Let $Seq(n,k)$ be the number of positive-integer sequences $\{a_i\}_{1 \le i \le n}$ of length $n$ such that:
- $n$ is divisible by $a_i$ for $1 \le i \le n$, and
- $n + a_1 + a_2 + \cdots + a_n$ is divisible by $k$.
Examples:
$Seq(3,4) = 4$, and the $4$ sequences are:
$\{1, 1, 3\}$
$\{1, 3, 1\}$
$\{3, 1, 1\}$
$\{3, 3, 3\}$
$Seq(4,11) = 8$, and the $8$ sequences are:
$\{1, 1, 1, 4\}$
$\{1, 1, 4, 1\}$
$\{1, 4, 1, 1\}$
$\{4, 1, 1, 1\}$
$\{2, 2, 2, 1\}$
$\{2, 2, 1, 2\}$
$\{2, 1, 2, 2\}$
$\{1, 2, 2, 2\}$
The last nine digits of $Seq(1111,24)$ are $840643584$.
Find the last nine digits of $Seq(1234567898765,4321)$.