jn⁡(z)=sin⁡(z-12⁢n⁢π)⁢∑k=0⌊n/2⌋(-1)k⁢a2⁢k⁡(n+12)z2⁢k+1+cos⁡(z-12⁢n⁢π)⁢∑k=0⌊(n-1)/2⌋(-1)k⁢a2⁢k+1⁡(n+12)z2⁢k+2.