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 A198400 #25 Aug 29 2024 20:59:55
%S A198400 1,0,80,970,9960,99950,999940,9999930,99999920,999999910,9999999900,
%T A198400 99999999890,999999999880,9999999999870,99999999999860,
%U A198400 999999999999850,9999999999999840,99999999999999830,999999999999999820,9999999999999999810,99999999999999999800,999999999999999999790
%N A198400 a(n) = 10^n - 10*n.
%H A198400 Vincenzo Librandi, <a href="/A198400/b198400.txt">Table of n, a(n) for n = 0..1000</a>
%H A198400 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (12,-21,10).
%F A198400 a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 2.
%F A198400 G.f.: (1-12*x+101*x^2)/((1-10*x)*(1-x)^2). - _Vincenzo Librandi_, Jul 06 2012
%F A198400 E.g.f.: exp(x)*(exp(9*x) - 10*x). - _Elmo R. Oliveira_, Aug 29 2024
%t A198400 CoefficientList[Series[(1-12*x+101*x^2)/((1-10*x)*(1-x)^2),{x,0,40}],x] (* _Vincenzo Librandi_, Jul 06 2012 *)
%o A198400 (Magma) [10^n-10*n: n in [0..25]];
%o A198400 (PARI) a(n)=10^n-10*n \\ _Charles R Greathouse IV_, Jul 06 2017
%Y A198400 Cf. A005803, A107583, A107584, A107585.
%K A198400 nonn,easy
%O A198400 0,3
%A A198400 _Vincenzo Librandi_, Oct 26 2011