Here is an example I have,

> evalf(sum(Zeta(p-2.)*2.9^p/GAMMA(.5000000000*p+1.), p = 4 .. infinity))

The Maple just returns me the same expression, but if I change the number "2.9" to be some other numbers (roughly >3 or <2.8), then Maple "will" give me the answers. What happened? Can anyone tell me why Maple refuse to do the work during that range of value (roughly between 2.8 to 3). It's even weird. If you change the initial index of the sum from...