- #1

- 76

- 0

[tex]{n + k-1 \choose n - 1} = \sum_{i=1}^k {k-1\choose i -1} {n \choose i}[/tex]

I've tried to figure out what the combinatorial meaning of the right hand side is, but I didn't succeed :(

- Thread starter Pietjuh
- Start date

- #1

- 76

- 0

[tex]{n + k-1 \choose n - 1} = \sum_{i=1}^k {k-1\choose i -1} {n \choose i}[/tex]

I've tried to figure out what the combinatorial meaning of the right hand side is, but I didn't succeed :(

- #2

- 53

- 0

[tex]{n + k-1 \choose k} = \sum_{i=1}^k {k-1\choose k - i} {n \choose i}[/tex]

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