Mine was simpler:
Divide each number by number before it you get a new series:
1,2,10,140,5740 >>> 2, 5 , 14 , 41
Now subtract each number by number before it you get a new series:
2, 5 , 14 , 41 >>> 3, 9, 27
The new series above is pretty clear, the next would be 81. Now we take it back above to the first series and it is 700280