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 A103456 #27 Feb 24 2024 01:10:21
%S A103456 1,9,99,999,9999,99999,999999,9999999,99999999,999999999,9999999999,
%T A103456 99999999999,999999999999,9999999999999,99999999999999,
%U A103456 999999999999999,9999999999999999,99999999999999999,999999999999999999
%N A103456 a(n) = 0^n + 10^n - 1.
%C A103456 A transform of 10^n under the matrix A103452.
%C A103456 Except for n = 0, the same as A002283. - _Felix Fröhlich_, Jun 22 2021
%H A103456 G. C. Greubel, <a href="/A103456/b103456.txt">Table of n, a(n) for n = 0..450</a>
%H A103456 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A103456 G.f.: (1 - 2*x + 10*x^2)/((1 - x)*(1 - 10*x));
%F A103456 a(n) = Sum_{k = 0..n} A103452(n, k)*10^k;
%F A103456 a(n) = Sum_{k = 0..n} (2*0^(n-k) - 1)*0^(k*(n-k))*10^k.
%F A103456 a(n) = A002283(n), n > 0. - _R. J. Mathar_, Aug 30 2008
%F A103456 E.g.f.: 1 - exp(x) + exp(10*x). - _G. C. Greubel_, Jun 21 2021
%t A103456 Table[Boole[n==0] + 10^n -1, {n,0,40}] (* _Alonso del Arte_, Nov 03 2019 *)
%o A103456 (Magma) [1] cat [10^n -1: n in [1..40]]; // _G. C. Greubel_, Jun 21 2021
%o A103456 (Sage) [1]+[10^n -1 for n in (1..40)] # _G. C. Greubel_, Jun 21 2021
%o A103456 (PARI) a(n) = 0^n + 10^n - 1 \\ _Felix Fröhlich_, Jun 22 2021
%o A103456 (PARI) Vec((1 - 2*x + 10*x^2)/((1 - x)*(1 - 10*x)) + O(x^20)) \\ _Felix Fröhlich_, Jun 22 2021
%Y A103456 Cf. A002283, A103452.
%K A103456 easy,nonn
%O A103456 0,2
%A A103456 _Paul Barry_, Feb 06 2005