Counting Arrays

Consider an array $$$a$$$ of length $$$n$$$ with elements numbered from $$$1$$$ to $$$n$$$. It is possible to remove the $$$i$$$-th element of $$$a$$$ if $$$gcd(a_i, i) = 1$$$, where $$$gcd$$$ denotes the greatest common divisor. After an element is removed, the elements to the right are shifted to the left by one position.

An array $$$b$$$ with $$$n$$$ integers such that $$$1 \le b_i \le n - i + 1$$$ is a removal sequence for the array $$$a$$$ if it is possible to remove all elements of $$$a$$$, if you remove the $$$b_1$$$-th element, then the $$$b_2$$$-th, ..., then the $$$b_n$$$-th element. For example, let $$$a = [42, 314]$$$:

• $$$[1, 1]$$$ is a removal sequence: when you remove the $$$1$$$-st element of the array, the condition $$$gcd(42, 1) = 1$$$ holds, and the array becomes $$$[314]$$$; when you remove the $$$1$$$-st element again, the condition $$$gcd(314, 1) = 1$$$ holds, and the array becomes empty.
• $$$[2, 1]$$$ is not a removal sequence: when you try to remove the $$$2$$$-nd element, the condition $$$gcd(314, 2) = 1$$$ is false.

An array is ambiguous if it has at least two removal sequences. For example, the array $$$[1, 2, 5]$$$ is ambiguous: it has removal sequences $$$[3, 1, 1]$$$ and $$$[1, 2, 1]$$$. The array $$$[42, 314]$$$ is not ambiguous: the only removal sequence it has is $$$[1, 1]$$$.

You are given two integers $$$n$$$ and $$$m$$$. You have to calculate the number of ambiguous arrays $$$a$$$ such that the length of $$$a$$$ is from $$$1$$$ to $$$n$$$ and each $$$a_i$$$ is an integer from $$$1$$$ to $$$m$$$.