\operatorname{arcsec} (x)\approx \sqrt{x - 1} \Biggl(\sqrt{2} - \frac{5 \sqrt{2} (x - 1)}{12} + \frac{43 \sqrt{2} (x - 1)^{2}}{160} - \\ \quad{}\quad{}\frac{177 \sqrt{2} (x - 1)^{3}}{896} + \frac{2867 \sqrt{2} (x - 1)^{4}}{18432} - \frac{11531 \sqrt{2} (x - 1)^{5}}{90112} + \\ \quad{}\quad{}\frac{92479 \sqrt{2} (x - 1)^{6}}{851968} - \frac{74069 \sqrt{2} (x - 1)^{7}}{786432} + \\ \quad{}\quad{}\frac{11857475 \sqrt{2} (x - 1)^{8}}{142606336} - \frac{47442055 \sqrt{2} (x - 1)^{9}}{637534208} + \\ \quad{}\quad{}\frac{126527543 \sqrt{2} (x - 1)^{10}}{1879048192} - \frac{1518418695 \sqrt{2} (x - 1)^{11}}{24696061952} + \\ \quad{}\quad{}\frac{24295375159 \sqrt{2} (x - 1)^{12}}{429496729600} - \frac{97182800711 \sqrt{2} (x - 1)^{13}}{1855425871872} + \\ \quad{}\quad{}\frac{777467420263 \sqrt{2} (x - 1)^{14}}{15942918602752} - \frac{3109879375897 \sqrt{2} (x - 1)^{15}}{68169720922112}\ldots\Biggr)

`&sepsequence`(`&nothing`,`&operatorname`(arcsec)(x),approx,nullspace,(x-1)^(1/2)*`&delimiter`(leftparens,rightparens,false,`&sepsequence`(`&nothing`,2^(1/2)-5/12*2^(1/2)*(x-1)+43/160*2^(1/2)*(x-1)^2-177/896*2^(1/2)*(x-1)^3+2867/18432*2^(1/2)*(x-1)^4-11531/90112*2^(1/2)*(x-1)^5+92479/851968*2^(1/2)*(x-1)^6-74069/786432*2^(1/2)*(x-1)^7+11857475/142606336*2^(1/2)*(x-1)^8-47442055/637534208*2^(1/2)*(x-1)^9+126527543/1879048192*2^(1/2)*(x-1)^10-1518418695/24696061952*2^(1/2)*(x-1)^11+24295375159/429496729600*2^(1/2)*(x-1)^12-97182800711/1855425871872*2^(1/2)*(x-1)^13+777467420263/15942918602752*2^(1/2)*(x-1)^14-3109879375897/68169720922112*2^(1/2)*(x-1)^15,ldots)))