This book contains papers on topics in combinatorics (including graph theory) or number theory. The subject areas within correspond to the MSC (Mathematics Subject Classification) codes 05, 11, 20D60, and 52. Some topics discussed in this compilation include restricted Eisenstein series and certain convolution sums; zeroes of the Hurwitz zeta function in the interval (O,1); prime factorization conditions providing multiplicities in coset partitions of groups; mean value formulas for twisted Edwards curves; binary matrices as morphisms of a triangular category; some diophantine triples and quadruples for quadratic polynomials; codes associated with orthogonal groups; combinatorial sums and series involving inverses of the Gaussian binomial coeffecients; full friendly index sets and full product-cordial index sets of twisted cylinders; and properly charged coloring of two-dimensional arrays.