Nuka-Cola formula is a paper note in the Fallout 4 add-on Nuka-World. It can be given to Sierra Petrovita for 500 caps if she is not killed.
An official looking folder, with a stamp on the outside cover. It does not allow the Sole Survivor to craft Nuka-Cola.
Found at the end of the Cappy in a Haystack quest in Bradberton's office, next to the Nuka-nuke schematics, by siding with John-Caleb Bradberton over Sierra Petrovita and cutting power to the vault.