"Hard" problem: Given $n$ points and $m$ edges, how many different connections can you form?
59247
How many connected graphs over V vertices and E edges?
45448
Minimum number of $k$-partitions of a set of size $n$ to enumerate all $n \choose k$ combinations
129752
How to find whether it is possible for each vertex of a graph to have a different degree?
63379
Enumerate non-isomorphic graphs on n vertices
87431
$n-$circular arrangement problem
49045
Graph theory: Tree holds two sub-tree with an amount of vertices
10910
How many edges does an undirected tree with $n$ nodes have?
117349
counting triangles in a graph or its complement
113902
Show that there's a unique minimum spanning tree if all edges have different costs
127965
Graph theory (Graph Connectivity)
108941
Combinatorics Question Asking How Many Integer Solutions Given Different Restrictions
154564
Prove that the sum of minimum edge cover and maximum matching is the vertex count
25382
Maximum number of edges in a bipartite graph
82372
Calculate possible lines from points
100832
Number of binary trees with $N$ nodes
123626
Prove that even $n$ can be partitioned to $\frac n2$ edges
65622
Maximum edges in a square free graph