I think I have the hang of this now, but I have a minor question:
I am to find the constant which would make satisfy all the conditions of being a p.m.f.
I assumed that this would continue on to infinity [for there was another similar to this, where it explicitly said that ]
So, I figured that ;
I also noticed that . The series is geometric, where , and . Thus, it converges to
However, my text tells me that the answer is 3.
Maybe I'm overlooking one simple thing...wait!
How do I apply the last property of a p.m.f:
to this problem?
I'd appreciate any input!