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 A171090 #18 Nov 19 2021 17:38:37 %S A171090 1,0,1,0,2,1,5,3,18,19,79,134,501,1147,3976,11055,37231,114560,384053, %T A171090 1244056,4193857,13977946,47522279,161222224,553033544,1899744032, %U A171090 6571595339,22793047258,79449718217,277760027418,974836112457 %N A171090 Number of Apollonian packings of n circles that are Eulerian and irreducible. %H A171090 G. Brinkmann, and B.D. McKay, <a href="http://users.cecs.anu.edu.au/~bdm/plantri/plantri-guide.txt">Guide to using plantri (version 4.1)</a>. %H A171090 Gunnar Brinkmann and Brendan McKay, <a href="/A007021/a007021.txt">Guide to using plantri</a> [Cached copy, with permission] %H A171090 S. Butler et al., <a href="http://dx.doi.org/10.1007/s00454-009-9216-9">Irreducible Apollonian configurations and packings</a>, Discrete and Computational Geometry, 44 (2010), 487-507. %H A171090 CombOS - Combinatorial Object Server, <a href="http://combos.org/plantri">Generate planar graphs</a> %K A171090 nonn %O A171090 6,5 %A A171090 _N. J. A. Sloane_, Sep 08 2010 %E A171090 More terms from plantri added by _Sean A. Irvine_, Jun 22 2016