Trying to find the next number for 3, -6, 12, 4, 20, ?

Question

I'm looking for answers

Answer 1

It appears by taking the difference of the numbers:

-9,+18,-8,+16

 

That the sequence is -#, then +2*#

So the next two numbers would have a -7 and then +14

 

So 20-7 = 13

13+14 = 27

Answer 2

3 - 9 = -6

-6 +18 = 12

12 -8 = 4
4 +16 = 20

 

The sequence of added is: -9, +18, -8, +16

 

So the next number in this sequence would be: -9, +18, -8, +16, -7, 

 

20 - 7 = 13

I suggest that the next number is 13.

 

This is my best suggestion. I would be happy to see if another tutor has a more

elegant sequence.