Combinatorial and Additive Number Theory IV

0. Math in the Time of Covid (M.B. Nathanson).- 1. Extremal sequences for some weighted zero-sum constants for cyclic groups (S.D. Adhikari, M.I. Molla, S. Paul).- 2. On a zero-sum problem arising from factorization theory (A. Bashir, A. Geroldinger, Q. Zhong).- 3. Conditional bounds on Siegel zeros (G. Bhowmik, K. Halupczok).- 4. Infinite co-minimal pairs in the integers and integral lattices (A. Biswas, J.P. Saha).- 5. Rigidity, graphs, and Hausdorff dimension (N. Chatzikonstantinou, A. Iosevich, S. Mkrtchyan, J. Pakianathan).- 6. On generalized harmonic numbers (Y.-G. Chen, B.-L. Wu).- 7. Partitions for semi-magic squares of size three (R. Donley).- 8. A sum of negative degrees of the gaps values in two-generated numerical semigroups and identities for the Hurwitz zeta function (L.G. Fel, T. Komatsu, A.I. Suriajaya).- 9. Widely digitally stable numbers (M. Filaseta, J. Juillerat, J. Southwick).- 10. Non-injectivity of nonzero discriminant polynomials and applications to packing polynomials (K. Gjaldbæk).- 11. Representing sequence subsums as sumsets of near equal sized sets (D.J. Grynkiewicz).- 12. Bounds on point configurations determined by distances and dot products (S. Gunter, E. Palsson, B. Rhodes, and S. Senger).- 13. Distribution of missing digits in diffsets (S. Harvey-Arnold, S.J. Miller, F. Peng).- 14. Recent progress in Hilbert cubes theory (N. Hegyvari).- 15. Intrinsic characterization of representation functions and generalizations (C. Helou).- 16. Combinatorics of multicompositions (B. Hopkins, S. Ouvrey).- 17. A variant of the Elliott-Halberstam conjecture and the Goldbach conjecture (J.-J. Huang, H. Li).- 18. Part-frequency matrices, II: Recent work (W. Keith).- 19. A conjectural inequality for visible points in lattice parallelograms (G. Khan, M.R. Khan, J. Saha, P. Zhao).- 20. On a two-dimensional exponential sum (A. Kumchev).- 21. On consecutive perfect powers