Shiny server pro machine requirements

I am new to Shiny Server Pro. I was wondering if anyone on this list can point me towards some guidelines for:

  • What are memory/core requirements do I need for hosting SSP ?
  • How much memory does the SSP server require?
    *How many cores would I need for 20, 50, or 100 concurrent users, running 2-5 different Rapps?
  • How does memory grow with # of concurrent users?

I know this may depend on the Rapp, but is there some baseline/minimum cost for memory or #cores?