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 A081044 #23 Jul 24 2016 21:22:40
%S A081044 1,17,225,2673,29889,321489,3365793,34543665,349156737,3486784401,
%T A081044 34480423521,338218086897,3295011258945,31914537622353,
%U A081044 307565765227809,2951106226689969,28207085096966913,268687927383516945
%N A081044 9th binomial transform of (1,8,0,0,0,0,0,0,.....).
%C A081044 Also number of (n+1)-digit numbers with exactly one '9' in their decimal expansion. Nine can be replaced by any nonzero digit 1..9. - _Zak Seidov_, Jul 11 2016
%H A081044 Vincenzo Librandi, <a href="/A081044/b081044.txt">Table of n, a(n) for n = 0..200</a>
%H A081044 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (18,-81).
%F A081044 a(n) = 18*a(n-1)-81*a(n-2), a(0)=0, a(1)=17.
%F A081044 a(n) = (8n+9)*9^(n-1).
%F A081044 a(n) = Sum_{k=0..n} (k+1)*8^k*binomial(n, k).
%F A081044 G.f.: (1-x)/(1-9x)^2.
%F A081044 E.g.f.: (1 + 8*x)*exp(9*x). - _Ilya Gutkovskiy_, Jul 18 2016
%t A081044 Table[(8n+9)9^(n-1),{n,0,30}] (*or*) LinearRecurrence[{18, -81}, {1, 17}, 40] (* _Vincenzo Librandi_, Feb 23 2012 *)
%o A081044 (PARI) a(n) = (8*n+9)*9^(n-1); \\ _Altug Alkan_, Jul 18 2016
%Y A081044 Cf. A081043, A081045.
%K A081044 base,easy,nonn
%O A081044 0,2
%A A081044 _Paul Barry_, Mar 04 2003