已知级数<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23817887_0.png"><img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23817887_0_1.png">则级数<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23817887_0_2.png">等于（　　）。