# Thread: combinatorical proof

1. ## combinatorical proof

Can please someone help me with this problem:

Prove:
$\sum_{k=1}^n \dfrac{1}{k} = \sum_{k=1}^n (-1)^{k-1} {n \choose k} \dfrac{1}{k}$

2. Originally Posted by barcica
Can please someone help me with this problem:

Prove:
$\sum_{k=1}^n \dfrac{1}{k} = \sum_{k=1}^n (-1)^{k-1} {n \choose k} \dfrac{1}{k}$
Off-hand I'd say there's a typo in this.