P6596 How Many of Them
Description
In an undirected connected graph, if removing an edge makes the graph split into two disconnected parts, then this edge is called a bridge.
Find the number of undirected connected graphs that satisfy the following conditions:
1. The graph consists of $n$ labeled vertices.
2. The number of bridges is at most $m$.
3. There are no multiple edges and no self-loops.
Output the answer modulo $10^{9}+7$.
Input Format
Only one line with two integers $n$ and $m$.
Output Format
One integer, representing the answer.
Explanation/Hint
Constraints: $2 \le n \le 50$, $0 \le m \le \dfrac{n(n-1)}{2}$.
Source: Gennady Korotkevich (tourist), ITMO University.
Translated by ChatGPT 5