cos(x) = (e^(ix) + e^(-ix))/2 ; cos(x)^20 = (e^(ix) + e^(-ix))^20/2^20 = = (1/2^20) sum_0^20 C(20,n) e^(i(20-n)x) e^(-inx) = = (1/2^20) sum_0^20 C(20,n) e^(i(20-2n)x) = = (1/2^20)(sum_0^9 C(20,n) (e^(i(20-2n)x)+e^(-i(20-2n)x))+C(20,10)) = C(20,10)/2^20 + (1/2^19) sum_1^10 C(20,10-n) cos(2n x) = = 46189/262144 + 20995 cos(2x)/65536 + 62985 cos(4x)/262144 + 4845 cos(6x)/32768 + 4845 cos(8x)/65536 + 969 cos(10x)/32768 + 4845 cos(12x)/524288 + 285 cos(14x)/131072 + 95 cos(16x)/262144 + 5 cos(18x)/131072 + cos(20x)/524288
León-Sotelo
