## Interesting number sequence

Here’s an interesting puzzle (*well for some people*). If I have the integers 4,5,6,7 and 8 and a special C function f so that f(4)=2, f(5) = 5, f(6)=10, f(7)=40 and f(8) = 92. What is the function f? And no it’s not a simple array containing the numbers 2,5,10,40,92 at positions 4-8!

I also checked the OEIS (*Online Encyclopaedia of Integer sequences*) and it’s not in there either. Years ago I was fooled by a integer sequence that was the maximum number of electrons in orbital shells but its definitely not that.

Here’s a minor clue. It is game related. Answer in a day or two.