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Fractions, prime, floor, sum
Fractions, prime, floor, sum
Source: 41 German Math Olympiad, Bundesrunde, Grade 13, P3
June 20, 2019
number theory
Problem Statement
Prove that for all primes
p
p
p
true is equality
∑
k
=
1
p
−
1
⌊
k
3
p
⌋
=
(
p
−
2
)
(
p
−
1
)
(
p
+
1
)
4
\sum_{k=1}^{p-1}\left\lfloor\frac{k^3}{p}\right\rfloor=\frac{(p-2)(p-1)(p+1)}{4}
k
=
1
∑
p
−
1
⌊
p
k
3
⌋
=
4
(
p
−
2
)
(
p
−
1
)
(
p
+
1
)
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