"Using the TeX \underbrace{1+3+5+\cdots}_n in a SC should result in the 'n' being underneath the brace. It is instead incorrectly positioned to the right of the brace (I think that this is the correct behaviour for TeX in inline mode)."
This is OU issue 6700, there are links to more information there if required.
Jonathan Darch says:
"Using the TeX \underbrace{1+3+5+\cdots}_n in a SC should result in the 'n' being underneath the brace. It is instead incorrectly positioned to the right of the brace (I think that this is the correct behaviour for TeX in inline mode)."
This is OU issue 6700, there are links to more information there if required.