mml=<math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="12px"><mfrac><mrow><mfenced separators="|"><mrow><mi mathvariant="normal">n</mi><mo>-</mo><mn>2</mn></mrow></mfenced><mo>+</mo><mfenced separators="|"><mrow><mi mathvariant="normal">n</mi><mo>-</mo><mn>1</mn></mrow></mfenced><mo>+</mo><mi mathvariant="normal">n</mi><mo>+</mo><mfenced separators="|"><mrow><mi mathvariant="normal">n</mi><mo>+</mo><mn>1</mn></mrow></mfenced><mo>+</mo><mfenced separators="|"><mrow><mi mathvariant="normal">n</mi><mo>+</mo><mn>2</mn></mrow></mfenced><mo>+</mo><mfenced separators="|"><mrow><mi mathvariant="normal">n</mi><mo>+</mo><mn>3</mn></mrow></mfenced><mo>+</mo><mo>(</mo><mi mathvariant="normal">n</mi><mo>+</mo><mn>4</mn><mo>)</mo></mrow><mn>7</mn></mfrac></mstyle></math>