“…In 1997, Langevin [9], as the generalization of [13], gave the evaluation of Gauss sums in the index 2 case for N = l r , where l is an odd prime, r 1. One year later, Mbodj [12], as the generalization of [17], gave the evaluation of Gauss sums in the index 2 case for N = l r1 1 l r2 2 , where l 1 , l 2 are distinct odd primes, r 1 , r 2 1. For N being power of 2, i.e., N = 2 t (t 3), Meijer and van der Vlugt [14], in 2003, evaluated the Gauss sums in the index 2 case and applied the results of Gauss sums to solving the problem of calculating the number of rational points for some algebraic curves over finite field.…”