Wn,4⁡(u,ξ)=|ξ|1/2⁢Yν⁡(u⁢|ξ|1/2)⁢∑s=0n-1As⁡(ξ)u2⁢s-|ξ|⁢Yν+1⁡(u⁢|ξ|1/2)⁢∑s=0n-2Bs⁡(ξ)u2⁢s+1+|ξ|1/2⁢env⁢Yν⁡(u⁢|ξ|1/2)⁢O⁡(1u2⁢n-1),