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 A318778 #54 May 27 2024 15:30:01 %S A318778 1,28,128,300,544,860,1248,1708,2240,2844 %N A318778 Number of different positions that an elementary sphinx can occupy in a sphinx of order n. %H A318778 Craig Knecht, <a href="/A318778/a318778.gif">33 positions that a flacon occupies in a S4 sphinx - animated.</a> %H A318778 Craig Knecht, <a href="/A318778/a318778_1.gif">Bottom row surface tension.</a> %H A318778 Craig Knecht, <a href="/A318778/a318778_1.png">Order Two Sphinx - 28 positions.</a> %H A318778 Craig Knecht, <a href="/A318778/a318778_2.png">Order three sphinx - 128 positions.</a> %H A318778 Craig Knecht, <a href="/A318778/a318778_4.png">Various shapes positioned in a order 4 sphinx.</a> %F A318778 Conjectures from _Colin Barker_, Nov 13 2018: (Start) %F A318778 G.f.: x*(1 + 25*x + 47*x^2 - x^3) / (1 - x)^3. %F A318778 a(n) = 44 - 80*n + 36*n^2 for n>1. %F A318778 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>4. %F A318778 (End) %Y A318778 Cf. A279887, A317541, A318897. %K A318778 nonn,more %O A318778 1,2 %A A318778 _Craig Knecht_, Sep 10 2018