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 A078672 #26 Jul 10 2025 02:51:46 %S A078672 0,0,0,0,0,0,1,1,6,16,59,188,685,2412,8825,32110,118505,437526, %T A078672 1624492,6043496,22553387,84345031,316183706,1187740914,4471145942, %U A078672 16864755973,63737132585,241337964503,915500561602 %N A078672 Number of simple 4-regular 4-edge-connected but not 3-connected plane graphs on n nodes. %H A078672 A. Caudron, <a href="http://sites.mathdoc.fr/PMO/PDF/C_CAUDRON_82_04.pdf">Classification des noeuds et des enlacements</a>, Public. Math. d'Orsay 82. Orsay: Univ. Paris Sud, Dept. Math., 1982. %H A078672 S. V. Jablan, <a href="http://members.tripod.com/vismath/sl/index.html">Ordering Knots</a> %H A078672 S. V. Jablan, L. M. Radović, and R. Sazdanović, <a href="http://eudml.org/doc/253048">Basic polyhedra in knot theory</a>, Kragujevac J. Math., 28 (2005), 155-164. %F A078672 a(n) = A078666(n) - A007022(n). %e A078672 The first such graph has 12 nodes. It is called 12E [Jablan, Radović & Sazdanović, Fig. 2; or Caudron, p. 308c] and looks like that: %e A078672 ___________ %e A078672 / \ %e A078672 / O---O O---O %e A078672 |/|\ /|\ /|\ /| %e A078672 O | O | O | O | %e A078672 |\|/ \|/ \|/ \| %e A078672 \ O---O O---O %e A078672 \___________/ %Y A078672 Cf. A007022, A078666. %K A078672 nonn,more %O A078672 6,9 %A A078672 Slavik V. Jablan and _Brendan McKay_, Feb 06 2003 %E A078672 a(23)-a(34) from _Sean A. Irvine_, Jul 09 2025