SOLUTION: nth element of sequences -1,2,-4,8 is

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Question 1000372: nth element of sequences -1,2,-4,8 is
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Each 'next element' is -2 times the previous element
So lets start with that
%28-2%29%5Ex where x>=0 and is an integer.
If we stop with this we end up with a sequence of 1, -2, 4 , -8 etc
So we are close, but the signs is wrong. So negate each element
-+%28-2%29%5Ex where x>=0 and is an integer.