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 A137195 #16 Apr 04 2024 09:49:52
%S A137195 1,6,19,64,185,542,1511,4144,11329,29894,80731,207696,556217,1405566,
%T A137195 3741263,9328928,24716353,60998086,161022115,394136864,1037382905,
%U A137195 2522256670,6622609463,16012527312,41958312193,100973218566
%N A137195 Even-indexed coefficients related to Kirchhoff index of hexagonal (benzene) chains.
%C A137195 Essentially CONV transform of A079496.
%H A137195 Vincenzo Librandi, <a href="/A137195/b137195.txt">Table of n, a(n) for n = 0..1000</a>
%H A137195 Yujun Yang and Heping Zhang, <a href="http://dx.doi.org/10.1002/qua.21537">Kirchhoff Index of linear hexagonal chains</a>, Int. J. Quant. Chem. 108 (2008) 503-512.
%H A137195 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (0,12,0,-38,0,12,0,-1).
%F A137195 O.g.f.: ((1+3*x-x^2-x^3)/(1-6*x^2+x^4))^2.
%F A137195 a(n) = 12*a(n-2)-38*a(n-4)+12*a(n-6)-a(n-8).
%t A137195 CoefficientList[Series[((1 + 3 x - x^2 - x^3)/(1 - 6 x^2 + x^4))^2, {x, 0, 40}], x] (* _Vincenzo Librandi_, Dec 12 2012 *)
%o A137195 (Magma) I:=[1,6,19,64,185,542,1511,4144]; [n le 8 select I[n] else 12*Self(n-2)-38*Self(n-4)+12*Self(n-6)-Self(n-8): n in [1..40]]; // _Vincenzo Librandi_, Dec 12 2012
%K A137195 easy,nonn
%O A137195 0,2
%A A137195 _R. J. Mathar_, Apr 04 2008