New in Wolfram Mathematica 7: Discrete Calculus  previous | next 
Explore Some Input Complete Classes of Sums
Sum can compute all sums for many classes of summands including polynomial, polynomial exponential, rational and rational exponential.

Click for copyable input

 With[{g = f /. n -> m}, 

  Text@TraditionalForm@Pane[g == ReleaseHold[g], 400]], {{m, 25, "n"},

   1, 50, 1}, {{f, HoldForm[Sum[k^n 3^k, k]], 

   "sum"}, {HoldForm[Sum[k^n, k]], HoldForm[Sum[k^n 3^k, k]], 

   HoldForm[Sum[1/(k (k + n)), k]], 

   HoldForm[Sum[2^k/(k (k + n)), k]]}}]