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 A155671 #22 Sep 08 2022 08:45:40
%S A155671 1,2,20,272,3440,40952,468560,5217032,56953280,612579512,6513215600,
%T A155671 68618940392,717570463520,7458134171672,77123207545040,
%U A155671 794108867905352,8146979811148160,83322818300333432,849905364703000880
%N A155671 a(n) = 10^n - 9^n + 1^n.
%C A155671 a(n) is the number of numbers from 1 to 10^n containing a 1 in their decimal expansion. - _Charles R Greathouse IV_, Mar 25 2009
%H A155671 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (20,-109,90).
%F A155671 G.f.: 1/(1-10*x)-1/(1-9*x)+1/(1-x).
%F A155671 E.g.f.: e^(10*x)-e^(9*x)+e^x.
%F A155671 a(n) = 19*a(n-1)-90*a(n-2)+72 with a(0)=1, a(1)=2. - _Vincenzo Librandi_, Jul 21 2010
%F A155671 a(n) = 20*a(n-1)-109*a(n-2)+90*a(n-3). - _Wesley Ivan Hurt_, Apr 21 2021
%t A155671 Table[10^n-9^n+1,{n,0,20}] (* or *) LinearRecurrence[{20,-109,90},{1,2,20},20] (* _Harvey P. Dale_, Nov 05 2017 *)
%o A155671 (PARI) a(n)=10^n-9^n+1^n \\ _Charles R Greathouse IV_, Oct 16 2015
%o A155671 (Magma) [10^n-9^n+1: n in [0..25]]; // _Wesley Ivan Hurt_, Apr 21 2021
%Y A155671 Equals A016189 + 1. See that entry for more information.
%Y A155671 Cf. A155654, A155655, A155656, A155657, A155658, A155659, A155660, A155661, A155662, A155663, A155664, A155665, A155666, A155667, A155668, A155669, A155670.
%K A155671 nonn,easy
%O A155671 0,2
%A A155671 _Mohammad K. Azarian_, Feb 01 2009