Hypergeometric Sequences!

Let $a, b, c$ be real numbers such that $-c$ is not a natural number. Find the condition for convergence of the hypergeometric series:

$\large\ \sum _{ n=1 }^{ \infty }{ \frac { a\left( a + 1 \right) \cdot \cdot \cdot \left( a + n - 1 \right) b\left( b + 1 \right) \cdot \cdot \cdot \left( b + n - 1 \right) }{ n!c\left( c + 1 \right) \cdot \cdot \cdot \left( c + n - 1 \right) } }$ .