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National and Regional Contests
PEN Problems
PEN K Problems
31
31
Part of
PEN K Problems
Problems
(1)
K 31
Source:
5/25/2007
Find all strictly increasing functions
f
:
N
ā
N
f: \mathbb{N}\to \mathbb{N}
f
:
N
ā
N
such that
f
(
f
(
n
)
)
=
3
n
.
f(f(n))=3n.
f
(
f
(
n
))
=
3
n
.
function
induction
Functional Equations