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 A244842 #45 Nov 12 2022 20:48:30
%S A244842 0,99,10989,1109889,111098889,11110988889,1111109888889,
%T A244842 111111098888889,11111110988888889,1111111109888888889,
%U A244842 111111111098888888889,11111111110988888888889,1111111111109888888888889,111111111111098888888888889,11111111111110988888888888889
%N A244842 a(n) = (10^n - 1)*(10^n - 10)/90.
%C A244842 For n > 1, the digit sums of a(n) are 18, 27, 36, ..., 9n (see example).
%H A244842 Jens Kruse Andersen, <a href="/A244842/b244842.txt">Table of n, a(n) for n = 1..100</a>
%H A244842 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
%F A244842 G.f.: -99*x / ( (x-1)*(100*x-1)*(10*x-1) ). - _R. J. Mathar_, Jul 11 2014
%F A244842 a(n) = 99*A109242(n-2). - _R. J. Mathar_, Jul 11 2014
%e A244842 -------------------------------------------------------
%e A244842 n a(n) digitsum(a(n)) 9*n
%e A244842 -------------------------------------------------------
%e A244842 2: 99 18 9*2
%e A244842 3: 10989 27 9*3
%e A244842 4: 1109889 36 9*4
%e A244842 5: 111098889 45 9*5
%e A244842 6: 11110988889 54 9*6
%e A244842 7: 1111109888889 63 9*7
%e A244842 8: 111111098888889 72 9*8
%e A244842 9: 11111110988888889 81 9*9
%e A244842 10: 1111111109888888889 90 9*10
%e A244842 11: 111111111098888888889 99 9*11
%e A244842 12: 11111111110988888888889 108 9*12, etc.
%p A244842 A244842:=n->(10^n - 1)*(10^n - 10)/90: seq(A244842(n), n=1..15);
%t A244842 Table[(10^n - 1) (10^n - 10)/90, {n, 15}]
%o A244842 (Magma) [(10^n-1)*(10^n-10)/90: n in [1..15]];
%Y A244842 Cf. A053422, A109242.
%K A244842 nonn,easy
%O A244842 1,2
%A A244842 _Wesley Ivan Hurt_, Jul 08 2014