Sequence <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle a_{n}=(-1)^{n}\cdot {\frac {n}{n+1}}}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><msub><mi>a</mi><mrow class="MJX-TeXAtom-ORD"><mi>n</mi></mrow></msub><mo>=</mo><mo stretchy="false">(</mo><mo>−<!-- − --></mo><mn>1</mn><msup><mo stretchy="false">)</mo><mrow class="MJX-TeXAtom-ORD"><mi>n</mi></mrow></msup><mo>⋅<!-- ⋅ --></mo><mrow class="MJX-TeXAtom-ORD"><mfrac><mi>n</mi><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></mfrac></mrow></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle a_{n}=(-1)^{n}\cdot {\frac {n}{n+1}}}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ab8ae3b1c2362acd5ed2ecb1a73a6b22ae944eef" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -2.005ex; width:19.458ex; height:4.843ex;" alt="{\displaystyle a_{n}=(-1)^{n}\cdot {\frac {n}{n+1}}}"></span> with two subsequences <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (a_{2k})}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mo stretchy="false">(</mo><msub><mi>a</mi><mrow class="MJX-TeXAtom-ORD"><mn>2</mn><mi>k</mi></mrow></msub><mo stretchy="false">)</mo></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle (a_{2k})}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/5e9f48ee383fafe03aee52da954cce722d65ab94" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.838ex; width:4.95ex; height:2.843ex;" alt="{\displaystyle (a_{2k})}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (a_{2k+1})}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mo stretchy="false">(</mo><msub><mi>a</mi><mrow class="MJX-TeXAtom-ORD"><mn>2</mn><mi>k</mi><mo>+</mo><mn>1</mn></mrow></msub><mo stretchy="false">)</mo></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle (a_{2k+1})}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f6921bc7a3ef33b268c6265bbf430551f7bf9df" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.838ex; width:7.05ex; height:2.843ex;" alt="{\displaystyle (a_{2k+1})}"></span>.
<a rel="nofollow" class="external text" href="http://kulla.me/">Stephan Kulla</a> (<a href="//commons.wikimedia.org/wiki/User:Stephan_Kulla" title="User:Stephan Kulla">User:Stephan Kulla</a>)
2015-05-29
<span class="int-own-work" lang="en">Own work</span>