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2017 CMIMC
2017 CMIMC Algebra
9
2017 A9: Sequence of Floors and Square Roots
2017 A9: Sequence of Floors and Square Roots
Source:
January 29, 2017
2017
algebra
Problem Statement
Define a sequence
{
a
n
}
n
=
1
∞
\{a_{n}\}_{n=1}^{\infty}
{
a
n
}
n
=
1
∞
via
a
1
=
1
a_{1} = 1
a
1
=
1
and
a
n
+
1
=
a
n
+
⌊
a
n
⌋
a_{n+1} = a_{n} + \lfloor \sqrt{a_{n}} \rfloor
a
n
+
1
=
a
n
+
⌊
a
n
⌋
for all
n
≥
1
n \geq 1
n
≥
1
. What is the smallest
N
N
N
such that
a
N
>
2017
a_{N} > 2017
a
N
>
2017
?
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