The sequence $(a_n)$ of real numbers satisfies for every positive integer $n$ $$a_{n+1} = a_n + \frac{(-1)^n \cdot a_n}{2}$$ the equality. If $a_5 = 18$, what is $a_1$? A) 4 B) 8 C) 16 D) 32 E) 64
The sequence $(a_n)$ of real numbers satisfies for every positive integer $n$
$$a_{n+1} = a_n + \frac{(-1)^n \cdot a_n}{2}$$
the equality. If $a_5 = 18$, what is $a_1$?\\
A) 4\\
B) 8\\
C) 16\\
D) 32\\
E) 64