Series

Answer is : 3,263,442




This is the series

 

1	2
2	6
6	42
42	1,806
1,806	3,263,442
3,263,442	10,650,056,950,806
10,650,056,950,806	113,423,713,055,422,000,000,000,000

Explain :     1,   2 ( 1*1 +1) , 6 ( 2*2+2), 42 (6*6+6) & so on..............