This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A011948 #24 Apr 15 2024 06:58:57 %S A011948 1,1,4,7,18,31,70,126,261,484,960,1800,3514,6643,12852,24457,47151, %T A011948 90157,173740,333498,643230,1238664,2392650,4620006,8939657,17302033, %U A011948 33538048,65042495,126289800,245361171,477153040,928510506,1808276211,3523813566,6871685532,13408154100,26178323928,51139027135 %N A011948 Number of Barlow packings with group P63mc that repeat after 2n layers. %H A011948 D. Bundala, M. Codish, L. Cruz-Filipe et al., <a href="http://arxiv.org/abs/1412.5302">Optimal-Depth Sorting Networks</a>, arXiv preprint arXiv:1412.5302 [cs.DS], 2014. (See Table 4) %H A011948 J. E. Iglesias, <a href="https://doi.org/10.1524/zkri.2006.221.4.237">Enumeration of closest-packings by the space group: a simple approach</a>, Z. Krist. 221 (2006) 237-245, Table 3. %H A011948 T. J. McLarnan, <a href="http://dx.doi.org/10.1524/zkri.1981.155.3-4.269">The numbers of polytypes in close-packings and related structures</a>, Zeits. Krist. 155, 269-291 (1981). %Y A011948 Appears to be column k=2 of A309784. %Y A011948 Cf. A045668. %K A011948 nonn %O A011948 6,3 %A A011948 _N. J. A. Sloane_