Calcium ammonium nitrate doesn't exist as a single, stable compound. Here's why:

* Calcium nitrate (Ca(NO₃)₂) and ammonium nitrate (NH₄NO₃) are both ionic compounds.

* They are typically used separately in fertilizers or other applications.

* While they could potentially exist in solution together, there is no known stable solid compound formed by combining these two ions directly.

Therefore, there is no specific chemical formula for calcium ammonium nitrate.