Question 1135558
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The formula describes a geometric progression with the first term a1 = -6 and the common ratio 4.


The first two sequences in optional answers do not have -6 as the first term, so they automatically go out of our consideration.


The third sequence is NOT a geometric, so it goes out, too . . . 


And only the last, #4 sequence, is what the question is asking for.
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