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PEN D Problems
7
7
Part of
PEN D Problems
Problems
(1)
D 7
Source:
5/25/2007
Somebody incorrectly remembered Fermat's little theorem as saying that the congruence
a
n
+
1
≡
a
(
m
o
d
n
)
a^{n+1} \equiv a \; \pmod{n}
a
n
+
1
≡
a
(
mod
n
)
holds for all
a
a
a
if
n
n
n
is prime. Describe the set of integers
n
n
n
for which this property is in fact true.
modular arithmetic
number theory
Congruences