On the number of spanning trees a planar graph can have
On the number of subsequences with a given sum in a finite abelian group
On the number of tetrahedra with minimum, unit, and distinct volumes in three-space
On the number of tilings of a square by rectangles
On the number of topological types occurring in a parametrized family of arrangements
On the number of Tverberg partitions in the prime power case
On the number of two-dimensional threshold functions
On the number of unlabeled vertices in edge-friendly labelings of graphs
On the number of vertices in integer linear programming problems
On the number of walks on a regular Cayley tree
On the optimality of the Arf invariant formula for graph polynomials
On the Orchard crossing number of complete bipartite graphs
On the Orchard crossing number of prisms, ladders and other related graphs
On the Order Dimension of Convex Geometries
On the Order Dimension of Outerplanar Maps
On the order of a non-abelian representation group of a slim dense near hexagon
On the ordering of trees by the Laplacian coefficients
On the orientation of graphs
On the Oriented Chromatic Number of Dense Graphs
On the outerplanar crossing numbers of complete multipartite graphs