What is the 6th number in this sequence?

1, 2, 6, 42, 1806,?

Thank you!

Well, you didn't ask for the formula, so just looking at the sequence:
1,2 can start a lot of different sequences
6 coming next - hmm 6 is 2*3 which is the previous number (2) times that number +1 (2+1=3)
So if we try that for the next number we have 6 * 6+1 = 6 * 7 = 42
and the next:
42 * 43 = 1806
so, for the next number
1806 * 1807 = 3263442 which I would say is your answer.
To go back and check the initial 2 numbers
1 * 1+1 = 2
so the answer should be valid since it complies with all available information.

From this, can you write the expression for the series?