Enable "MathML (experimental; no images)" or "Client side MathJax rendering" in Special:Preferences → Apperance → Math. Then preview a page with the contents <blockquote></blockquote>Let <math>n</math> be an integer or alternatively: Let <math>n</math> be an integer <div style="display: float"></div>.

I expect to see:

Let n be an integer

but it actually looks like

Let
n
be an integer

See https://en.wikipedia.org/wiki/Autoencoder#Definition for another example.

It displays fine using SVG math or when a new paragraph is inserted to separate the blockquote or <div> element from the math markup. The issue appears to be that too many <p> elements are inserted by the wikitext parser as this issue can be "fixed" by adding the CSS rule p {display: inline} in browser devtools.