Much tougher to get a sequential than a dealt royal. The odds of a dealt royal is 1:649,740. But the first question is the sequential reversible or not. You can make a sequential two ways, either A-K-Q-J-T or T-J-Q-K-A. On most machines that have a sequential it's reversible.
Without a strategy shift the odds of a reversible sequential is 1 in 60 royals.
Just hypothetical here but if a 9/6 Jacks had a reversible on it, and without a strategy shift, then the frequency would be 40,391 X 60 = 2,423,460
When you make a royal it can appear 120 different ways. The first card can be any one of the 5, the second card can be any one of the remaining 4, the third card can be any one of the remaining 3, the fourth card can be any one of the remaining 2, and the fifth card is whatever is left.
5X4X3X2X1 = 120
So the chances of a reversible sequential is 1 in 60 when you make a royal.