MathDB
Sequence y1, y2, y3, ...

Source: CMO 1993 Problem 5

January 25, 2007

Problem Statement

Let y1,y2,y3,y_{1}, y_{2}, y_{3},\ldots be a sequence such that y1=1y_{1}=1 and, for k>0,k>0, is defined by the relationship: y2k={2ykif k is even2yk+1if k is oddy_{2k}=\begin{cases}2y_{k}& \text{if}~k~ \text{is even}\\ 2y_{k}+1 & \text{if}~k~ \text{is odd}\end{cases}y2k+1={2ykif k is odd2yk+1if k is eveny_{2k+1}=\begin{cases}2y_{k}& \text{if}~k~ \text{is odd}\\ 2y_{k}+1 & \text{if}~k~ \text{is even}\end{cases}Show that the sequence takes on every positive integer value exactly once.