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All-Russian Olympiad
1989 All Soviet Union Mathematical Olympiad
490
490
Part of
1989 All Soviet Union Mathematical Olympiad
Problems
(1)
ASU 490 All Soviet Union MO 1989 12 positive divisors, d_m=(d_1+d_2+d_4)d_8
Source:
8/13/2019
A positive integer
n
n
n
has exactly
12
12
12
positive divisors
1
=
d
1
<
d
2
<
d
3
<
.
.
.
<
d
12
=
n
1 = d_1 < d_2 < d_3 < ... < d_{12} = n
1
=
d
1
<
d
2
<
d
3
<
...
<
d
12
=
n
. Let
m
=
d
4
−
1
m = d_4 - 1
m
=
d
4
−
1
. We have
d
m
=
(
d
1
+
d
2
+
d
4
)
d
8
d_m = (d_1 + d_2 + d_4) d_8
d
m
=
(
d
1
+
d
2
+
d
4
)
d
8
. Find
n
n
n
.
number theory
divisor