The number of matroids on a finite set

The number of maximum matchings in a tree

The number of monotone triangles with prescribed bottom row

The number of nilpotent semigroups of degree 3

The Number of Nowhere-Zero Flows on Graphs and Signed Graphs

The number of occurrences of a fixed spread among n directions in vector spaces over finite fields

The number of permutations realized by a shift

The number of permutations with a given number of sequences

The Number of Permutations With A Prescribed Number of 132 and 123 Patterns

The number of permutations with k inversions

The number of point-splitting circles

The number of points in a matroid with no n-point line as a minor

The number of rhombus tilings of a "punctured" hexagon and the minor summation formula

The number of rhombus tilings of a symmetric hexagon which contain a fixed rhombus on the symmetry axis, I

The number of rhombus tilings of a symmetric hexagon which contain a fixed rhombus on the symmetry axis, II

The number of ribbon Schur functions

The Number of Same-Sex Marriages in a Perfectly Bisexual Population is Asymptotically Normal

The number of terms in the permanent and the determinant of a generic circulant matrix

The number of unit distances is almost linear for most norms

The Number of Ways to Assemble a Graph