Problem A. 376. (May 2005)
A. 376. Is it possible to obtain the array (5,13,42) starting from (1,21,42) by repeating the following steps: It is allowed to swap any two numbers in an array of three numbers (a,b,c), or replace the array by (a,b,2a+2b-c).
Deadline expired on 15 June 2005.