Straight Jacks side bet

The Casino del Sol in Tucson has a new side bet called Straight Jacks. If your first 2 cards are a straight, regardless of suit, you win 3 for 1. If your next card makes a 3 card straight you win 25 for 1. A 4-card straight pays 100 for 1. And, a 5 card straight pays 250 for 1. I've been playing it and it seems to be paying off nicely. How would I calculate the actual odds for this thing?