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 A294344 #13 Mar 12 2018 16:10:50
%S A294344 1,9,79,679,5679,45679,345679,2345679,12345679,12345679,-987654321,
%T A294344 -20987654321,-320987654321,-4320987654321,-54320987654321,
%U A294344 -654320987654321,-7654320987654321,-87654320987654321,-987654320987654321,-10987654320987654321,-120987654320987654321
%N A294344 a(n) = ((-9*n + 82)*10^n - 1)/81.
%H A294344 Colin Barker, <a href="/A294344/b294344.txt">Table of n, a(n) for n = 0..900</a>
%H A294344 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (21,-120,100).
%F A294344 From _Colin Barker_, Oct 29 2017: (Start)
%F A294344 G.f.: (1 - 12*x + 10*x^2) / ((1 - x)*(1 - 10*x)^2).
%F A294344 a(n) = 21*a(n-1) - 120*a(n-2) + 100*a(n-3) for n>2.
%F A294344 (End)
%e A294344 Curious multiplications:
%e A294344 9 * 8 = 72;
%e A294344 79 * 8 = 632;
%e A294344 679 * 8 = 5432;
%e A294344 5679 * 8 = 45432;
%e A294344 45679 * 8 = 365432;
%e A294344 345679 * 8 = 2765432;
%e A294344 2345679 * 8 = 18765432.
%e A294344 9 * 9 = 81;
%e A294344 79 * 9 = 711;
%e A294344 679 * 9 = 6111;
%e A294344 5679 * 9 = 51111;
%e A294344 45679 * 9 = 411111;
%e A294344 345679 * 9 = 3111111;
%e A294344 2345679 * 9 = 21111111.
%t A294344 LinearRecurrence[{21,-120,100},{1,9,79},30] (* _Harvey P. Dale_, Mar 12 2018 *)
%o A294344 (PARI) Vec((1 - 12*x + 10*x^2) / ((1 - x)*(1 - 10*x)^2) + O(x^30)) \\ _Colin Barker_, Oct 29 2017
%Y A294344 Cf. A294328.
%K A294344 sign,easy
%O A294344 0,2
%A A294344 _Seiichi Manyama_, Oct 28 2017