If I am asking something stupid, I'm sorry. I was helping one of my academic brother with his course. And I came to this formula:
$\sum_{n=-\infty}^\infty z^{n^2}=\prod_{m=1}^\infty (1-z^m)(1-z^{m+1/2})^2.$
I am confused whether the mass inside of the "$\displaystyle\prod_{m=1}^\infty$'' is correct. Shouldn't it be the inverse of the multiplicand?
Thanks for any comment!