Pustam | पुस्तम | পুস্তম🇳🇵<p>A lattice sum with a surprising closed form:<br />\[\Large\displaystyle\sum_{\substack{(m,n)\in\mathbb Z^2\\(m,n)\neq0}}\dfrac{1}{(m+ni)^4}=\dfrac{\varpi^4}{15}=\dfrac{\Gamma^8\left(\frac14\right)}{960\pi^2}\]<br /><a href="https://mathstodon.xyz/tags/LatticeSum" class="mention hashtag" rel="tag">#<span>LatticeSum</span></a> <a href="https://mathstodon.xyz/tags/ClosedForm" class="mention hashtag" rel="tag">#<span>ClosedForm</span></a> <a href="https://mathstodon.xyz/tags/LemniscateConstant" class="mention hashtag" rel="tag">#<span>LemniscateConstant</span></a> <a href="https://mathstodon.xyz/tags/Series" class="mention hashtag" rel="tag">#<span>Series</span></a> <a href="https://mathstodon.xyz/tags/Sum" class="mention hashtag" rel="tag">#<span>Sum</span></a> <a href="https://mathstodon.xyz/tags/GammaFunction" class="mention hashtag" rel="tag">#<span>GammaFunction</span></a> <a href="https://mathstodon.xyz/tags/Pi" class="mention hashtag" rel="tag">#<span>Pi</span></a></p>