\operatorname{cosh} (x) = 1 + \frac{1}{2} x^{2} + \frac{1}{24} x^{4} + \frac{1}{720} x^{6} + \frac{1}{40320} x^{8} + \frac{1}{3628800} x^{10} + \\ \quad{}\quad{}\frac{1}{479001600} x^{12} + \frac{1}{87178291200} x^{14} + \operatorname{O} \bigl(x^{16}\bigr)

`&operatorname`(cosh)(x) = series(1+1/2*x^2+1/24*x^4+1/720*x^6+1/40320*x^8+1/3628800*x^10+1/479001600*x^12+1/87178291200*x^14+O(x^16),x,16)