37th Austrian Mathematical Olympiad 2006
Source: round2, problem1
February 10, 2009
functionnumber theory unsolvednumber theory
Problem Statement
Let be a non-negative integer, which ends written in decimal notation on exactly zeros, but which is bigger than .
For a is only k\equal{}k(n)\geq2 known. In how many different ways (as a function of k\equal{}k(n)\geq2) can be written as difference of two squares of non-negative integers at least?