Absolute reference:
HACS:asympt:1:RDINREFRDGENFROMRDCLOSED
u (n) = \frac{2^{\bigl(n + \frac{1}{2}\bigr)} \Gamma \Bigl(n + \frac{1}{2}\Bigr) (-1)^{n}}{4^{n} \sqrt{\pi} \Gamma (n + 1) (2 n + 1)}
u(n) = 2^(n+1/2)*4^(-n)/Pi^(1/2)/GAMMA(n+1)/(2*n+1)*GAMMA(n+1/2)*(-1)^n
<math xmlns='http://www.w3.org/1998/Math/MathML'><semantics><mrow xref='id36'><mrow xref='id3'><mi xref='id1'>u</mi><mo>⁡</mo><mfenced><mi xref='id2'>n</mi></mfenced></mrow><mo>=</mo><mrow xref='id35'><mfrac><mrow xref='id21'><mrow><mrow><mrow xref='id8'><msup><mn xref='id4'>2</mn><mfenced><mrow xref='id7'><mi xref='id5'>n</mi><mo>+</mo><mfrac xref='id6'><mn>1</mn><mn>2</mn></mfrac></mrow></mfenced></msup></mrow><mo>⁢</mo><mrow xref='id12'><msup><mn xref='id9'>4</mn><mfenced><mrow xref='id11'><mo>-</mo><mi xref='id10'>n</mi></mrow></mfenced></msup></mrow></mrow><mo>⁢</mo><mrow xref='id17'><mi>Γ</mi><mo>⁡</mo><mfenced><mrow xref='id16'><mi xref='id14'>n</mi><mo>+</mo><mfrac xref='id15'><mn>1</mn><mn>2</mn></mfrac></mrow></mfenced></mrow></mrow><mo>⁢</mo><mrow xref='id20'><msup><mfenced><mn xref='id18'>-1</mn></mfenced><mi xref='id19'>n</mi></msup></mrow></mrow><mrow xref='id34'><mrow><mrow xref='id23'><msqrt><mn xref='id22'>π</mn></msqrt></mrow><mo>⁢</mo><mrow xref='id28'><mi>Γ</mi><mo>⁡</mo><mfenced><mrow xref='id27'><mi xref='id25'>n</mi><mo>+</mo><mn xref='id26'>1</mn></mrow></mfenced></mrow></mrow><mo>⁢</mo><mfenced><mrow xref='id33'><mrow xref='id31'><mn xref='id29'>2</mn><mo>⁢</mo><mi xref='id30'>n</mi></mrow><mo>+</mo><mn xref='id32'>1</mn></mrow></mfenced></mrow></mfrac></mrow></mrow><annotation-xml encoding='MathML-Content'><apply id='id36'><eq/><apply id='id3'><ci id='id1'>u</ci><ci id='id2'>n</ci></apply><apply id='id35'><divide/><apply id='id21'><times/><apply id='id8'><power/><cn id='id4' type='integer'>2</cn><apply id='id7'><plus/><ci id='id5'>n</ci><cn id='id6' type='rational'>1<sep/>2</cn></apply></apply><apply id='id12'><power/><cn id='id9' type='integer'>4</cn><apply id='id11'><minus/><ci id='id10'>n</ci></apply></apply><apply id='id17'><csymbol id='id13' definitionURL='http://www.maplesoft.com/MathML/GAMMA'>GAMMA</csymbol><apply id='id16'><plus/><ci id='id14'>n</ci><cn id='id15' type='rational'>1<sep/>2</cn></apply></apply><apply id='id20'><power/><cn id='id18' type='integer'>-1</cn><ci id='id19'>n</ci></apply></apply><apply id='id34'><times/><apply id='id23'><root/><pi id='id22'/></apply><apply id='id28'><csymbol id='id24' definitionURL='http://www.maplesoft.com/MathML/GAMMA'>GAMMA</csymbol><apply id='id27'><plus/><ci id='id25'>n</ci><cn id='id26' type='integer'>1</cn></apply></apply><apply id='id33'><plus/><apply id='id31'><times/><cn id='id29' type='integer'>2</cn><ci id='id30'>n</ci></apply><cn id='id32' type='integer'>1</cn></apply></apply></apply></apply></annotation-xml><annotation encoding='Maple'>u(n) = 2^(n+1/2)*4^(-n)/Pi^(1/2)/GAMMA(n+1)/(2*n+1)*GAMMA(n+1/2)*(-1)^n</annotation></semantics></math>