パデ近似
C ( x ) ≈ ( 1 / 135 ) ⋅ ( 990791 x 9 π 4 − 147189744 x 5 π 2 + 8714684160 x ) ( 1749 π 4 x 8 + 523536 π 2 x 4 + 64553216 ) {\displaystyle C(x)\approx {\frac {(1/135)\cdot (990791x^{9}\pi ^{4}-147189744x^{5}\pi ^{2}+8714684160x)}{(1749\pi ^{4}x^{8}+523536\pi ^{2}x^{4}+64553216)}}}