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Problems
Contests
National and Regional Contests
Turkey Contests
National Olympiad First Round
2013 National Olympiad First Round
31
31
Part of
2013 National Olympiad First Round
Problems
(1)
P31 [Algebra] - Turkish NMO 1st Round - 2013
Source:
4/20/2013
Let
(
a
n
)
n
=
1
∞
(a_n)_{n=1}^\infty
(
a
n
)
n
=
1
∞
be a real sequence such that
a
n
=
(
n
−
1
)
a
1
+
(
n
−
2
)
a
2
+
⋯
+
2
a
n
−
2
+
a
n
−
1
a_n = (n-1)a_1 + (n-2)a_2 + \dots + 2a_{n-2} + a_{n-1}
a
n
=
(
n
−
1
)
a
1
+
(
n
−
2
)
a
2
+
⋯
+
2
a
n
−
2
+
a
n
−
1
for every
n
≥
3
n\geq 3
n
≥
3
. If
a
2011
=
2011
a_{2011} = 2011
a
2011
=
2011
and
a
2012
=
2012
a_{2012} = 2012
a
2012
=
2012
, what is
a
2013
a_{2013}
a
2013
?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
6025
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
5555
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
4025
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
3456
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
2013
<span class='latex-bold'>(A)</span>\ 6025 \qquad<span class='latex-bold'>(B)</span>\ 5555 \qquad<span class='latex-bold'>(C)</span>\ 4025 \qquad<span class='latex-bold'>(D)</span>\ 3456 \qquad<span class='latex-bold'>(E)</span>\ 2013
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
6025
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
5555
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
4025
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
3456
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
2013