I have a problem to solve, the problem is:
Is the language of strings
$$L=\{0^x1^y:x\nmid y\}$$
context free?
I suspect it isn't, I spent some time trying to make a grammar that could generate that language, but I couldn't and I don't know how to prove it.
Here's a set of production rules that produce the strings, which seems to fail the Wikipedia definition of context-free grammar.
$S \rightarrow 1 S$
$1S \rightarrow S0$
$S0 \rightarrow \emptyset$
As far as the restriction you mentioned on the produced strings, I don't know how that factors in. Hopefully this can help you.