What is the recursive definition for $\displaystyle 1 + (-1)^n $?
so then using n = 1
$\displaystyle
a_(1+1) = a_2
= a_1 + (-1)^1 *2
= 0 + (-1)*2
= -2
$
doesn't it? but doesn't $\displaystyle a_2 = 2 $ and not -2
I think your solution will work with (-1)^(n+1) instead of $\displaystyle (-1)^n $
Am I right?
Thanks for everyones help! =]