Each LOLcat Gives birth to 672 other LOLcats in its lifetime.
Another hint: The number of new LOLcats born each iteration (30 minutes) follows the series 1,2,6,18,54,162... I think you see the pattern.
If N=the number of cats born on the 17,520th iteration,
So the answer is 672 x (1+2+6+18+54........+(n/3^672))+671(n/3^671)+670(n/3^670)+......