# Math Help - Convergence question

1. ## Convergence question

How do I show that SUM n-1Ck-1 converges..and it would also be helpful to show what it converges to. Thanks im a little rusty

2. Do you mean $\sum\binom{n-1}{k-1}$? What is the index of summation? What set does it range over? Is this an infinite series?