algebra precalculus - How to find summation of the series $1 + frac {1}{3} + frac {1cdot 3}{3cdot 6} +cdots$

How to find summation of the series $1 + \dfrac {1}{3} + \dfrac {1\cdot 3}{3\cdot 6} + \dfrac {1\cdot 3\cdot 5}{3\cdot 6\cdot 9} + \dfrac {1\cdot 3\cdot 5\cdot 7}{3\cdot 6\cdot 9\cdot 12} + .....$ ?

I can't find any particular sequence.Please help!