- #1

- 2

- 0

[itex]\sum[/itex]

^{n}

_{k=0}([itex]\frac{n}{k}[/itex]) = 2

^{n}

But what if you want to sum from any arbitrary k, like 4? I've tried looking at Pascal's triangle for nice values of n and k, but haven't been able to see a pattern. I would really appreciate any help with this. I want to apply this to combinations for large n, which are impractical to compute.

Thank you in advance.