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 A116176 #29 Mar 10 2025 13:56:42
%S A116176 0,18,486,8748,131220,1771470,22320522,267846264,3099363912,
%T A116176 34867844010,383546284110,4142299868388,44059007691036,
%U A116176 462619580755878,4804126415541810,49413871702715760,504021491367700752
%N A116176 a(n) = 9^n * n*(n+1).
%H A116176 Vincenzo Librandi, <a href="/A116176/b116176.txt">Table of n, a(n) for n = 0..1000</a>
%H A116176 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (27,-243,729).
%F A116176 G.f.: 18*x/(1-9*x)^3. - _Vincenzo Librandi_, Feb 28 2013
%F A116176 a(n) = 27*a(n-1) - 243*a(n-2) + 729*a(n-3). - _Vincenzo Librandi_, Feb 28 2013
%F A116176 a(n) = 18*A081139(n+1). - _Bruno Berselli_, Mar 01 2013
%F A116176 E.g.f.: 9*x*(2 + 9*x)*exp(9*x). - _G. C. Greubel_, May 11 2019
%F A116176 From _Amiram Eldar_, Jul 20 2020: (Start)
%F A116176 Sum_{n>=1} 1/a(n) = 1 - 8*log(9/8).
%F A116176 Sum_{n>=1} (-1)^(n+1)/a(n) = 10*log(10/9) - 1. (End)
%t A116176 Table[(n^2 + n) 9^n, {n, 0, 20}] (* _Vincenzo Librandi_, Feb 28 2013 *)
%o A116176 (Magma) [(n^2+n)*9^n: n in [0..20]]; // _Vincenzo Librandi_, Feb 28 2013
%o A116176 (PARI) {a(n) = 9^n*n*(n+1)}; \\ _G. C. Greubel_, May 11 2019
%o A116176 (Sage) [9^n*n*(n+1) for n in (0..20)] # _G. C. Greubel_, May 11 2019
%o A116176 (GAP) List([0..20], n-> 9^n*n*(n+1)); # _G. C. Greubel_, May 11 2019
%Y A116176 Cf. A007758, A036289, A081139, A128796.
%K A116176 nonn,easy
%O A116176 0,2
%A A116176 _Mohammad K. Azarian_, Apr 08 2007