1 1 1 1 1 1 1 1 1 1
------ + ------ + ------ + ------ + ------- + ------- + ------- + ------- + ------- + -------
2 4 6 8 10 12 14 16 18 20
1 + x 1 + x 1 + x 1 + x 1 + x 1 + x 1 + x 1 + x 1 + x 1 + x
$$\frac{1}{x^{20} + 1} + \frac{1}{x^{18} + 1} + \frac{1}{x^{16} + 1} + \frac{1}{x^{14} + 1} + \frac{1}{x^{12} + 1} + \frac{1}{x^{10} + 1} + \frac{1}{x^{8} + 1} + \frac{1}{x^{6} + 1} + \frac{1}{x^{4} + 1} + \frac{1}{x^{2} + 1}$$
1/(1 + x^2) + 1/(1 + x^4) + 1/(1 + x^6) + 1/(1 + x^8) + 1/(1 + x^10) + 1/(1 + x^12) + 1/(1 + x^14) + 1/(1 + x^16) + 1/(1 + x^18) + 1/(1 + x^20)