Mathematics

Problem

z + \frac{1}{z} = 1

and

a = z^{2017} + \frac{1}{z^{2017}}

and

b

is the last digit of the number

2^{2^n} - 1

, when the integer

n > 1

, the value of

a^2 + b^2

is a. 23 b. 24 c. 26 d. 27