Here is the code:
open Printf
let n = int_of_string Sys.argv.(1)
let k = int_of_string Sys.argv.(2)
There is no call to mountainsnumber at the outermost level of this code. So if this is your complete code, it just computes values for n and k, and then defines some functions. This will produce no output, because the defined functions are never called.
If this is the problem you just need to add a call to mountainsnumber at the end. Something like this:
let () = mountainsnumber n k
Update
(Hmm, you have edited your post to remove all the content. So this comment doesn't make a lot of sense any longer.)