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 A081278 #18 Jan 02 2024 08:52:41
%S A081278 1,6,29,126,513,1998,7533,27702,99873,354294,1240029,4290894,14703201,
%T A081278 49955454,168466797,564390342,1879706817,6227425638,20533285917,
%U A081278 67411165086,220442258241,718277586606,2332658764269,7552375012566
%N A081278 Binomial transform of Chebyshev polynomial coefficients A001793.
%H A081278 Vincenzo Librandi, <a href="/A081278/b081278.txt">Table of n, a(n) for n = 0..1000</a>
%H A081278 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-27,27).
%F A081278 a(n) = (n^2+8*n+9)3^(n-2).
%F A081278 G.f.: (1-2*x)*(1-x)/(1-3x)^3.
%t A081278 CoefficientList[Series[(1 - 2 x) (1 - x) / (1 - 3 x)^3, {x, 0, 40}], x] (* _Vincenzo Librandi_, Aug 07 2013 *)
%o A081278 (Magma) [(n^2+8*n+9)*3^(n-2): n in [0..25]]; // _Vincenzo Librandi_, Aug 07 2013
%Y A081278 Cf. A007051, A006234, A081279.
%K A081278 nonn,easy
%O A081278 0,2
%A A081278 _Paul Barry_, Mar 16 2003