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 A115400 #29 Feb 16 2025 08:33:00
%S A115400 0,0,0,6,96,780,4080,15330,45696,115416,257760,523710,987360,1752036,
%T A115400 2957136,4785690,7472640,11313840,16675776,24006006,33844320,46834620,
%U A115400 63737520,85443666,112987776,147563400,190538400,243471150,308127456
%N A115400 Number of n-colorings of the octahedral graph.
%C A115400 The octahedral graph is the dual of the cubical graph whose chromatic polynomial is evaluated in A140986.
%H A115400 Vincenzo Librandi, <a href="/A115400/b115400.txt">Table of n, a(n) for n = 0..10000</a>
%H A115400 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/OctahedralGraph.html">Octahedral Graph</a>.
%H A115400 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).
%F A115400 a(n) = n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32).
%F A115400 G.f.: 6*x^3*(1 + 9*x + 39*x^2 + 71*x^3)/(1-x)^7. - _Colin Barker_, Feb 12 2012
%F A115400 a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n > 6. - _Chai Wah Wu_, Jan 19 2024
%t A115400 Table[n*(n-1)*(n-2)*(n^3-9*n^2+29*n-32),{n,0,50}] (* _Vincenzo Librandi_, Feb 12 2012 *)
%o A115400 (Magma) [n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32): n in [0..50]]; // _Vincenzo Librandi_, Feb 12 2012
%o A115400 (Maxima) A115400(n):=n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32)$
%o A115400 makelist(A115400(n),n,0,30); /* _Martin Ettl_, Nov 03 2012 */
%Y A115400 Cf. A140986.
%K A115400 easy,nonn
%O A115400 0,4
%A A115400 _Jonathan Vos Post_, Aug 25 2008