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 A155593 #20 Sep 09 2022 18:58:54
%S A155593 1,10,84,736,6576,59080,531504,4783096,43046976,387421000,3486785424,
%T A155593 31381061656,282429540576,2541865836520,22876792471344,
%U A155593 205891132127416,1853020188917376,16677181699797640,150094635297261264
%N A155593 a(n) = 9^n + 2^n - 1.
%H A155593 Harvey P. Dale, <a href="/A155593/b155593.txt">Table of n, a(n) for n = 0..1000</a>
%H A155593 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (12,-29,18).
%F A155593 G.f.: 1/(1-9*x)+1/(1-2*x)-1/(1-x).
%F A155593 E.g.f.: e^(9*x)+e^(2*x)-e^x.
%F A155593 a(n) = 11*a(n-1)-18*a(n-2)-8 with a(0)=1, a(1)=10. - _Vincenzo Librandi_, Jul 21 2010
%F A155593 a(n) = A074604(n)-1. - _R. J. Mathar_, Mar 10 2022
%t A155593 Table[9^n+2^n-1,{n,0,30}] (* or *) LinearRecurrence[{12,-29,18},{1,10,84},30] (* _Harvey P. Dale_, Sep 09 2022 *)
%o A155593 (PARI) a(n)=9^n+2^n-1^n \\ _Charles R Greathouse IV_, Jun 11 2015
%Y A155593 Cf. A074501, A074600, A005057, A005056, A099393, A155588, A155590, A155592.
%K A155593 nonn,easy
%O A155593 0,2
%A A155593 _Mohammad K. Azarian_, Jan 24 2009