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Canada National Olympiad
1993 Canada National Olympiad
5
Sequence y1, y2, y3, ...
Sequence y1, y2, y3, ...
Source: CMO 1993 Problem 5
January 25, 2007
Problem Statement
Let
y
1
,
y
2
,
y
3
,
…
y_{1}, y_{2}, y_{3},\ldots
y
1
,
y
2
,
y
3
,
…
be a sequence such that
y
1
=
1
y_{1}=1
y
1
=
1
and, for
k
>
0
,
k>0,
k
>
0
,
is defined by the relationship:
y
2
k
=
{
2
y
k
if
k
is even
2
y
k
+
1
if
k
is odd
y_{2k}=\begin{cases}2y_{k}& \text{if}~k~ \text{is even}\\ 2y_{k}+1 & \text{if}~k~ \text{is odd}\end{cases}
y
2
k
=
{
2
y
k
2
y
k
+
1
if
k
is even
if
k
is odd
y
2
k
+
1
=
{
2
y
k
if
k
is odd
2
y
k
+
1
if
k
is even
y_{2k+1}=\begin{cases}2y_{k}& \text{if}~k~ \text{is odd}\\ 2y_{k}+1 & \text{if}~k~ \text{is even}\end{cases}
y
2
k
+
1
=
{
2
y
k
2
y
k
+
1
if
k
is odd
if
k
is even
Show that the sequence takes on every positive integer value exactly once.
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