AwesomeMath 2006 - 2011, University of Texas at Dallas, University of Santa Cruz
University of Nebraska (Lincoln) - AMC (October 2001-January 2002), University of Ancona, Italy (November 1999), University of Heidelberg, Germany (May-June, 1997), University of Utrecht, Netherlands (May, 1997), Fern Universität Hagen, Germany (December, 1993), Middle East Technical University of Ankara, Turkey (July, 1990), Kind Saud University, Riyadh, Saudi Arabia (2010 - 2012), Columbus State University, Columbus, Georgia, USA (August - December 2014).
D.Andrica, T.Andreescu, On a Diophantine Equation and its Ramifications, The College Mathematics Journal, Vol. 35, No.1, January 2004
D.Andrica, L.Funar, On smooth maps with finitely many critical points, Journal of London Mathematical Society (2) 69(2004), 783-800
Functions with minimal critical set: new results and open problems, "Mathematical Analysis and Applications", Th.M. Rassias editor, Hadronic Press, Palm Harbor, 1999, 1-10.
An inequality concerning symmetric functions and some applications, "Recent Progess in Inequalities", G.V.Milovanovic editor, Kluwer Academic Publiser, Dordrecht/Boston/London, 1998, 425-431 (with L.Mare).
On some consequnces of a critical point result, Korean J. Math. Sciences 5(1998), 129-134 (with C.Pintea).
Other Professional Activities
Member in Editorial Board: Studia Univ. "Babeș-Bolyai"-Mathematica, Bakan Journal of Geometry, Gazeta Matematica, Acta Matematica Apulensis, Buletin of Calcutta Mathematical Society, General Mathematics, Mathematics Education
Co-organizer of the European Summer School "Spaces with singularities and monopols", Cluj-Napoca, 1999
Andrica' s Conjecture
"If Pn denotes the n-th prime number, then for all n greater than 1 the inequality is true:"
This seems to be a very hard open problem in Number Theory.