ag-gipp/GoUldI

<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ψ</mi><mfenced close=")" open="("><mfrac><mrow><mi>z</mi><mo>+</mo><mn>1</mn></mrow><mn>2</mn></mfrac></mfenced><mo>-</mo><mi>ψ</mi><mfenced close=")" open="("><mfrac><mi>z</mi><mn>2</mn></mfrac></mfenced><mo>=</mo><mn>2</mn><msubsup><mo>∑</mo><mrow><mi>k</mi><mo>=</mo><mn>0</mn></mrow><mi>∞</mi></msubsup><mfrac><msup><mfenced close=")" open="("><mn>-1</mn></mfenced><mi>k</mi></msup><mrow><mi>k</mi><mo>+</mo><mi>z</mi></mrow></mfrac></math>