K(μ)
=
ln4k'+122(ln4k'−21⋅2)(k′)2+(1⋅32⋅4)2(ln4k'−21⋅2−23⋅4)(k′)4+(1⋅3⋅52⋅4⋅6)2(ln4k'−21⋅2−23⋅4−25⋅6)(k′)6+⋯
Gradshteyn & Ryzhik (1965), §8.113.3
where: k'≡(1−μ2)1/2