3, -4, 7, -12, 19, ...

What is the next number in the sequence? What is the formula for the nth term of the sequence?

Thanks in advance!

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- Apr 20th 2010, 04:57 PMmeggnogWhat is the sequence formula?
3, -4, 7, -12, 19, ...

What is the next number in the sequence? What is the formula for the nth term of the sequence?

Thanks in advance! - Apr 20th 2010, 05:05 PMDeadstar
-28

Will think of definite formula for nth term. Hold on. - Apr 20th 2010, 05:08 PMpickslides
Hi there, consider the following.

The absolute differences from each term follows a pattern $\displaystyle 1,3,5,7,\dots $

Every the sign of every second term alternates. And looking at the differences after breaking the patterns into positive and negative numbers you get are $\displaystyle 4,8,12,\dots$

__Spoiler__: - Apr 20th 2010, 05:12 PMDeadstar