Direct expression for sum of squares

[cscott]

How do you go from $$\sum_{n = 1}^n i^2$$ to $$\frac{n(n + 1)(2n + 1)}{6}$$?

 

[arildno]

Prove the formula by induction.

 

[dicerandom]

I think you forgot to include something, what you wrote should simplify to $n i^2$.

Edit: Unless I'm missing something

 

[arildno]

Oops, the index should be i, not n as you've written.

 

[0rthodontist]

Yes, the index should be changed. See Robert Ihnot's post in this thread
https://www.physicsforums.com/showthread.php?t=108928

 

[cscott]

Thanks for the info.

My mistake with the index.