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2008 IMS
8
Find all numbers
Find all numbers
Source: IMS 2008
May 10, 2008
modular arithmetic
number theory proposed
number theory
Problem Statement
Find all natural numbers such that
n
σ
(
n
)
≡
2
(
m
o
d
ϕ
(
n
)
)
n\sigma(n)\equiv 2\pmod {\phi( n)}
nσ
(
n
)
≡
2
(
mod
ϕ
(
n
))
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