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National and Regional Contests
Iran Contests
Iran MO (2nd Round)
1983 Iran MO (2nd round)
7
7
Part of
1983 Iran MO (2nd round)
Problems
(1)
Find the sum - [Iran Second Round 1983]
Source:
12/30/2010
Find the sum
∑
i
=
1
∞
n
2
n
.
\sum_{i=1}^{\infty} \frac{n}{2^n}.
∑
i
=
1
∞
2
n
n
.
geometric series