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 A155673 #20 Oct 05 2024 16:30:24
%S A155673 1,20,220,2330,24640,261050,2771560,29487170,314358880,3357947690,
%T A155673 35937424600,385311670610,4138428376720,44522712143930,
%U A155673 479749833583240,5177248169415650,55949729863572160,605447028499293770
%N A155673 a(n) = 11^n + 10^n - 1.
%H A155673 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (22,-131,110).
%F A155673 G.f.: 1/(1-11*x)+1/(1-10*x)-1/(1-x).
%F A155673 E.g.f.: e^(11*x)+e^(10*x)-e^x.
%F A155673 a(n) = 21*a(n-1)-110*a(n-2)-90 with a(0)=1, a(1)=20. - _Vincenzo Librandi_, Jul 21 2010
%F A155673 a(n) = 22*a(n-1)-131*a(n-2)+110*a(n-3). - _Wesley Ivan Hurt_, May 19 2024
%t A155673 Table[11^n+10^n-1,{n,0,20}] (* _Harvey P. Dale_, Feb 24 2011 *)
%Y A155673 Cf. A155654, A155655, A155656, A155657, A155658, A155659, A155660, A155661, A155662, A155663, A155664, A155665, A155666, A155667, A155668, A155669, A155670, A155671, A155672.
%K A155673 nonn,easy
%O A155673 0,2
%A A155673 _Mohammad K. Azarian_, Feb 01 2009