<math xmlns='http://www.w3.org/1998/Math/MathML'><semantics><mrow xref='id17'><mrow xref='id15'><mrow xref='id5'><mi xref='id1'>n</mi><mo>⁢</mo><mrow xref='id4'><mi xref='id2'>u</mi><mo>⁡</mo><mfenced><mi xref='id3'>n</mi></mfenced></mrow></mrow><mo>+</mo><mrow xref='id14'><mfenced><mrow xref='id8'><mi xref='id6'>n</mi><mo>+</mo><mn xref='id7'>2</mn></mrow></mfenced><mo>⁢</mo><mrow xref='id13'><mi xref='id9'>u</mi><mo>⁡</mo><mfenced><mrow xref='id12'><mi xref='id10'>n</mi><mo>+</mo><mn xref='id11'>2</mn></mrow></mfenced></mrow></mrow></mrow><mo>=</mo><mn xref='id16'>0</mn></mrow><annotation-xml encoding='MathML-Content'><apply id='id17'><eq/><apply id='id15'><plus/><apply id='id5'><times/><ci id='id1'>n</ci><apply id='id4'><ci id='id2'>u</ci><ci id='id3'>n</ci></apply></apply><apply id='id14'><times/><apply id='id8'><plus/><ci id='id6'>n</ci><cn id='id7' type='integer'>2</cn></apply><apply id='id13'><ci id='id9'>u</ci><apply id='id12'><plus/><ci id='id10'>n</ci><cn id='id11' type='integer'>2</cn></apply></apply></apply></apply><cn id='id16' type='integer'>0</cn></apply></annotation-xml><annotation encoding='Maple'>n*u(n)+(n+2)*u(n+2) = 0</annotation></semantics></math>