I'm stuck on this problem:
$$1 + {1\cdot2\over1\cdot3} + {1\cdot2\cdot3\over1\cdot3\cdot5}+ {1\cdot2\cdot3\cdot4\over 1\cdot3\cdot5\cdot7} +\cdots$$
I've simplified the numerators $n!$ but can't figure out how to represent the denominators.
How do I go about solving this?