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Putnam
1987 Putnam
A6
A6
Part of
1987 Putnam
Problems
(1)
Putnam 1987 A6
Source:
8/5/2019
For each positive integer
n
n
n
, let
a
(
n
)
a(n)
a
(
n
)
be the number of zeroes in the base 3 representation of
n
n
n
. For which positive real numbers
x
x
x
does the series
∑
n
=
1
∞
x
a
(
n
)
n
3
\sum_{n=1}^\infty \frac{x^{a(n)}}{n^3}
n
=
1
∑
∞
n
3
x
a
(
n
)
converge?
Putnam