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Contests
National and Regional Contests
Sweden Contests
Swedish Mathematical Competition
1991 Swedish Mathematical Competition
3
3
Part of
1991 Swedish Mathematical Competition
Problems
(1)
x_0 = 0, x_{k+1} = [(n - \sum_0^k x_i)/2
Source: 1991 Swedish Mathematical Competition p3
4/2/2021
The sequence
x
0
,
x
1
,
x
2
,
.
.
.
x_0, x_1, x_2, ...
x
0
,
x
1
,
x
2
,
...
is defined by
x
0
=
0
x_0 = 0
x
0
=
0
,
x
k
+
1
=
[
(
n
−
∑
0
k
x
i
)
/
2
]
x_{k+1} = [(n - \sum_0^k x_i)/2]
x
k
+
1
=
[(
n
−
∑
0
k
x
i
)
/2
]
. Show that
x
k
=
0
x_k = 0
x
k
=
0
for all sufficiently large
k
k
k
and that the sum of the non-zero terms
x
k
x_k
x
k
is
n
−
1
n-1
n
−
1
.
Sequence
algebra