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 A110807 #13 Sep 08 2022 08:45:20
%S A110807 0,9,198,2997,39996,499995,5999994,69999993,799999992,8999999991,
%T A110807 99999999990,1099999999989,11999999999988,129999999999987,
%U A110807 1399999999999986,14999999999999985,159999999999999984
%N A110807 n times largest n-digit number.
%H A110807 G. C. Greubel, <a href="/A110807/b110807.txt">Table of n, a(n) for n = 0..990</a>
%H A110807 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (22,-141,220,-100).
%F A110807 a(n) = n*(10^n-1) = 9*A053422(n). - _R. J. Mathar_, Dec 04 2016
%F A110807 G.f.: -9*x*(-1+10*x^2) / ( (10*x-1)^2*(x-1)^2 ). - _R. J. Mathar_, Dec 04 2016
%e A110807 a(3) = 3*999 = 2997.
%t A110807 Table[(10^n - 1)*n, {n, 1, 30}] (* _Stefan Steinerberger_ *)
%t A110807 LinearRecurrence[{22,-141,220,-100},{0,9,198,2997,39996},20] (* _Harvey P. Dale_, Sep 22 2016 *)
%o A110807 (PARI) for(n=1,25, print1(n*(10^n-1), ", ")) \\ _G. C. Greubel_, Oct 19 2017
%o A110807 (Magma) [n*(10^n-1): n in [1..25]]; // _G. C. Greubel_, Oct 19 2017
%K A110807 base,easy,nonn
%O A110807 0,2
%A A110807 _Amarnath Murthy_, Aug 14 2005