M ν 2 ( x ) ∼ 2 π x ( 1 + 1 2 μ − 1 ( 2 x ) 2 + 1 ⋅ 3 2 ⋅ 4 ( μ − 1 ) ( μ − 9 ) ( 2 x ) 4 + 1 ⋅ 3 ⋅ 5 2 ⋅ 4 ⋅ 6 ( μ − 1 ) ( μ − 9 ) ( μ − 25 ) ( 2 x ) 6 + ⋯ ) {M_{\nu}^{2}}\left(x\right)\sim\frac{2}{\pi x}\left(1+\frac{1}{2}\frac{\mu-1}{(2x)^{2}}+\frac{1\cdot 3}{2\cdot 4}\frac{(\mu-1)(\mu-9)}{(2x)^{4}}+\frac{1\cdot 3\cdot 5}{2\cdot 4\cdot 6}\frac{(\mu-1)(\mu-9)(\mu-25)}{(2x)^{6}}+\cdots\right)