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 A158749 #23 Sep 09 2024 15:13:37
%S A158749 0,9,162,2187,26244,295245,3188646,33480783,344373768,3486784401,
%T A158749 34867844010,345191655699,3389154437772,33044255768277,
%U A158749 320275094369454,3088366981419735,29648323021629456,283512088894331673,2701703435345984178,25666182635786849691,243153309181138576020
%N A158749 a(n) = n*9^n.
%H A158749 Vincenzo Librandi, <a href="/A158749/b158749.txt">Table of n, a(n) for n = 0..200</a>
%H A158749 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (18,-81).
%F A158749 a(n) = n*9^n.
%F A158749 From _R. J. Mathar_, Mar 26 2009: (Start)
%F A158749 a(n) = 18*a(n-1) - 81*a(n-2) = A038299(n,1).
%F A158749 G.f.: 9*x/(1-9*x)^2. (End)
%F A158749 a(n) = A001019(n)*n. - _Omar E. Pol_, Mar 26 2009
%F A158749 From _Amiram Eldar_, Jul 20 2020: (Start)
%F A158749 Sum_{n>=1} 1/a(n) = log(9/8).
%F A158749 Sum_{n>=1} (-1)^(n+1)/a(n) = log(10/9). (End)
%F A158749 E.g.f.: 9*x*exp(9*x). - _Elmo R. Oliveira_, Sep 09 2024
%t A158749 Table[n 9^n, {n, 0, 20}] (* _Vincenzo Librandi_, Feb 25 2014 *)
%o A158749 (PARI) a(n) = n*9^n; \\ _Joerg Arndt_, Feb 23 2014
%o A158749 (Magma) [n*9^n: n in [0..20]]; // _Vincenzo Librandi_, Feb 25 2014
%Y A158749 Cf. A001019, A018215, A036289, A036290, A036291, A036292, A036293, A036294.
%Y A158749 Cf. A038299, A126431.
%K A158749 nonn,easy
%O A158749 0,2
%A A158749 _Zerinvary Lajos_, Mar 25 2009