XOR Hashing

Every point on a plane whose $x$ and $y$ coordinates are integers with $0 \leq x, y < 2^N$ is assigned the value $x \oplus y$, the XOR of its two coordinates. Mapping data to other data this way is called hashing, and the mapped value is called the hash value.

A point with an assigned value is chosen $M$ times. Each choice is made with equal probability, and the same point may be chosen more than once. Find the probability that two of the chosen points have the same hash value.

The first line contains integers $N$ and $M$ separated by a space. $(1 \leq N \leq 20;$ $1 \leq M \leq 10^9)$

Let the probability that two chosen points share a hash value be $\frac{p}{q}$, where $p$ and $q$ are coprime non-negative integers and $q\not\equiv 0 \pmod{10^9+7}$. Print $p\times q^{-1}\bmod (10^9+7)$. $q^{-1}$ is the modular multiplicative inverse of $q$.

You can prove that the probability is always a rational number.