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Problems
Contests
International Contests
Pan African
2002 Pan African
3
3
Part of
2002 Pan African
Problems
(1)
Write with 1 and 2
Source: Pan African 2002
8/20/2005
Prove for every integer
n
>
0
n>0
n
>
0
, there exists an integer
k
>
0
k>0
k
>
0
such that
2
n
k
2^nk
2
n
k
can be written in decimal notation using only digits 1 and 2.