list of pair

Hello, 

I try to create a cartesian product :

 [[10,1],[10,2],[10,3],[10,4],[10,5],[10,6],
  [20,1],[20,2],[20,3],[20,4],[20,5],[20,6],
  [30,1],[30,2],[30,3],[30,4],[30,5],[30,6]]

but I can't !

[[10*i,j] for i in 1..3 for j in 1..6]  constructs [[10,1],[20,2],[30,3]]
[([10*i,j] for i in 1..3) for j in 1..6] constructs a Tupple, not a list.
[[[10*i,j] for i in 1..3] for j in 1..6] constructs a List List ...

How can I do this ?

Have a good day !

Francois