Danube Mathematical Competition 2007 Problem 4
Source: Beautiful problem with beautiful combinatorial solution
December 8, 2007
number theoryprime numbersnumber theory proposed
Problem Statement
Let be positive integers such that a\ge(n\minus{}1)!. Prove that there exist distinct prime numbers so that p_i|a\plus{}i, for all i\equal{}\overline{1,\ldots,n}.