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Brazil Undergrad MO
2021 Brazil Undergrad MO
Problem 3
Problem 3
Part of
2021 Brazil Undergrad MO
Problems
(1)
Almost Square-minus-constant
Source: Brazilian Undergrad MO 2021 Problem 3
5/13/2022
Find all positive integers
k
k
k
for which there is an irrational
α
>
1
\alpha>1
α
>
1
and a positive integer
N
N
N
such that
⌊
α
n
⌋
\left\lfloor\alpha^{n}\right\rfloor
⌊
α
n
⌋
is of the form
m
2
−
k
m^2-k
m
2
−
k
com
m
∈
Z
m \in \mathbb{Z}
m
∈
Z
for every integer
n
>
N
n>N
n
>
N
.
Brazilian Undergrad MO 2021
real analysis
powers
irrational number
approximation
Perfect Square