[racket] issue with function "regexp-replaces"

I have to clean up a bunch of source files that don't show properly

I have a file from which I'm reading a bunch of regular expressions to replace, things like this: 

(#px"(?i:%5C)""/") 

but included in the same file (full of from-to pairs) are a bunch of straight string replacements, like this: 

("…""\\…")


I cannot figure out what's wrong with this one: what to do here

("\n""\n<br>")

it replaces the starting "\n" but never puts in the replacement "\n" 

I've doubled/tripled/quadrupled on the backslashes

("\n""\\n<br>")
("\n""\\\n<br>")

but that doesn't put in a newline, rather two separate characters,  "backslash" and "n"

any hints what I'm doing wrong here?