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Putnam
1962 Putnam
A5
Putnam 1962 A5
Putnam 1962 A5
Source: Putnam 1962
May 29, 2022
Putnam
binomial coefficients
Combinatorial Identity
Problem Statement
Evaluate
∑
k
=
0
n
(
n
k
)
k
2
.
\sum_{k=0}^{n} \binom{n}{k}k^{2}.
k
=
0
∑
n
(
k
n
)
k
2
.
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