This is an implementation of the algorithms counting and finding quadratic equations of the power mapping y = x^a over GF(2^n), proposed in [1] and [2].
[1] Y. Nawaz, K. C. Gupta, and G. Gong. Algebraic Immunity of S-Boxes Based on Power Mappings: Analysis and Construction. IEEE Transactions on Information Theory, 55(9):4263-4273, 2009.
[2] K. C. Gupta and I. G. Ray. Finding Biaffine and Quadratic Equations for S-Boxes Based on Power Mappings. IEEE Transactions on Information Theory, 61(4):2200-2209, 2015.