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

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