1. An explicit formula for the number of different (non isomorphic) simple graphs with $p$ vertices and $q$ edges
  2. 7 red, 5 green, 8 orange and 4 blue balls

  3. Set version of ramsey type problem

  4. A "strong" Galois-Tukey connection between orders with suborders

  5. Showing an alternating integer series is never $0$
  6. Does there exist a nonsingular graph for which the determinant of its adjacency matrix remains the same upon deleting a vertex?
  7. Do these classes of bidirected multigraphs with prescribed number of perfect matchings exist?

  8. Is Cauchy induction used for proofs other than for AM–GM?
  9. Identical Binary Matrices
  10. Generating Uniquely k-Optimal Point Sets

  11. How to prove the combinatorial equality?

  12. When is an induced subgraph of a Johnson graph hamilton-connected?

  13. Finding a semi-sparse vertex in a grid

  14. Elements of Coxeter group whose simple reflections pairwise commute

  15. Commutative algebra for the Conway games
  16. Lovász conjecture and 2-connected graphs

  17. Spectrum of orthogonality graph (2)
  18. Asymptotic distribution of $\lambda_1$ under the $z$-measure for partitions

  19. spectrum of orthogonality graphs
  20. Choosing $K$ "centers" from the space of permutations
  21. If we take a small subset of a sparse/uniform set system, how uniform can we arrange for the subset to be?
  22. Is the sum $\sum\limits_{j=0}^{k-1}(-1)^{j+1}(k-j)^{2k-2} \binom{2k+1}{j} \ge 0?$
  23. Representing meet-semilattices with vector spaces of specified dimensions

  24. Ordinary Generating Function for OEIS A056296?

  25. H-generalized join graph
  26. Question on a generalized Dirichlet series
  27. Number of zeros of the derivatives of a polynomial
  28. count the number of words in a set

  29. Multiset to set operator
  30. The Golay-Rudin-Shapiro sequence as “Hankel transform”

  31. The factorial of -1, -2, -3,

  32. "Edge Density" of Infinite Planar Graphs

  33. Colouring Positive Integers
  34. Minuscule weights of parabolic sub-root systems are not far from dominant

  35. Bounds on degrees of minors obtained by edge contractions of regular graphs
  36. What is the number of achiral color patterns for a row of n colors containing k different colors?

  37. Zero-sum partition of an abelian group

  38. Rim hook decomposition and volume of moduli spaces

  39. Combinatorial computational problem about 0-1 vectors and sampling algorithms

  40. Smallest $k$ such that every vector is a linear combination of at most $k$ generators

  41. How many length-24 Type III codes have no words of Hamming weight 3?

  42. What is known about the plethysm $\text{Sym}^d(\bigwedge^3 \mathbb{C}^6)$

  43. Number of full-rank matrices over a finite field with a full weight
  44. Non-trivial parity maps in graphs

  45. Where on the internet I can find database of graphs?
  46. Iterated automorphism groups of finite groups

  47. vector partition
  48. Mysterious symmetry - in search for a bijection

  49. Quantified imbalance in signed graphs

  50. Is the difference sequence of the maximum size of $k$-colorable subgraph non-increasing?

  51. Regular unimodular triangulation for a certain simplex

  52. Number of zeros of quadratic equation over finite fields

  53. Relationship of Weisfeiler-Lehman algorithm to weak isomorphism of coherent algebras

  54. Evaluation of a combinatorial sum (that comes from random matrices)

  55. identity involving generating sum over colored plane partitions
  56. Existence of bipartite subgraphs satisfying degree and edge cardinality constraints

  57. Relations between Betti numbers for clique complex
  58. Modification of the subset sum problem - "perfect coverage" of the set with good solutions

  59. Some divisibility constraints in Frobenius coin problem

  60. What's the motivation of entropy as a combinatorical tool? What problems is it able to solve?
  61. Birthday Inequality for non uniform distribution with specific collision entropy
  62. Simplest form for sum of Binomial Expressions
  63. What are some examples of interesting uses of the theory of combinatorial species?

  64. A recursion for the total number of 1's in binary expansions of the first natural numbers?

  65. New edge coloring problem in graph theory

  66. Show that $L$ is distributive if and only if $I_L$ is prime

  67. Number of homomorphisms from graph $H$ to $G$ , bounds that have to do with fractional coloring number?

  68. Counting transitive generators according to coset type

  69. Sum of products of binomials

  70. Probability of zero in a random matrix
  71. Expected value of maximal accumulation of functions $f:\{1,\ldots,n\} \to \{1,\ldots,n\}$
  72. Minimal period for a bounded Langton's ant moving on a tessellation

  73. Time for Langton's ant to cover a "square" torus

  74. Ham Sandwich Theorem with an extra condition

  75. Explicit Formula of Delsarte's Linear Programming Upper Bound for $A_q(n,3)$
  76. Alternative parallel paths
  77. How many Tic Tac Toe games are possible?
  78. universality of Macdonald polynomials
  79. Ramsey type theorem

  80. Partition set into equal-sum subsets

  81. Generic words of given weight

  82. The combinations of a finite multiset
  83. Largest $A\subset \mathbb{F}_2^n$ such that no two $a\neq b$ in $A$ add to an element of $A.$

  84. simulate coin tossing by die tossing
  85. Stronger than Frankl conjecture, with no "closure hypothesis"
  86. Classification of quasi-hereditary Nakayama algebras

  87. Two variable delta-finite function

  88. Bipartite Graphs arising from two k-partitions of a given Graph
  89. Maximum number of edges on $2^{k-1}+s$ vertices of a $k$-dimensional cube?
  90. Ramsey's theorem for the first uncountable ordinal
  91. Characterizing positivity of formal group laws

  92. Matroid isomorphism

  93. Ideals with the same Hilbert series

  94. large arithmetic progression modulo p (II)
  95. A variation of longest paths in directed acyclic graph

  96. Families of subsets whose characteristic vectors are spanning sets
  97. abundance of "full" couples
  98. Unrestricting The Parameters of a Functional Equation
  99. Number of Symmetric matrices of fix rank over finite fields

  100. Testing simplicial complexes for shellability