A compact packing of the plane with non-overlapping binary discs (two sizes of circles) with a radius ratio of 0.5451510421. The packing fraction (area density) is 0.911627478. This is the largest possible density for plane packings of binary circles with this radius ratio.<a rel="nofollow" class="external autonumber" href="https://arxiv.org/abs/math/0412418">[1]</a> This has a <a href="https://en.wikipedia.org/wiki/Wallpaper_group" class="extiw" title="w:Wallpaper group">wallpaper group</a> <i>p</i>31<i>m</i>.
<a href="//commons.wikimedia.org/wiki/User:99of9" title="User:99of9">Toby Hudson</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>, following Tom Kennedy <a rel="nofollow" class="external autonumber" href="https://arxiv.org/abs/math/0407145v2">[2]</a>, <a rel="nofollow" class="external autonumber" href="https://arxiv.org/abs/math/0412418v1">[3]</a>