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 A011949 #13 Jul 08 2025 02:43:12 %S A011949 0,0,1,2,6,12,28,56,119,240,496,990,2016,4032,8121,16256,32640,65268, %T A011949 130816,261630,523747,1047552,2096128,4192200,8386554,16773120, %U A011949 33550216,67100670,134209536,268418820,536854528,1073709056,2147450383,4294901760,8589869022,17179737120,34359607296 %N A011949 Number of Barlow packings with group P6(bar)m2 that repeat after 2n layers. %H A011949 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 A011949 T. J. McLarnan, <a href="https://doi.org/10.1524/zkri.1981.155.3-4.269">The numbers of polytypes in close packings and related structures</a>, Zeitschr. Krist. 155, 269-291 (1981). %K A011949 nonn,easy %O A011949 1,4 %A A011949 _N. J. A. Sloane_ %E A011949 More terms from _M. F. Hasler_, May 28 2025