Find the next three terms in each sequence.

1.
a, 3b, 6c, 9d, __ , __ , __

2.
1/2 , 1/3, 1/4 , __ , __ , __

3.
A, D, G, J, __ , __ , __

4.

3, 1, -1, -3, __ , __ , __

5.

1, 4, 9, 16, __ , __ , __

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