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 A089903 #22 Mar 26 2024 14:46:13
%S A089903 0,1,48,960,14572,195684,2456796,29567908,345679020,3956790132,
%T A089903 44567901244,495679012356,5456790123468,59567901234580,
%U A089903 645679012345692,6956790123456804,74567901234567916,795679012345679028
%N A089903 Sum of digits of numbers between 0 and (1/9)*(10^n-1).
%C A089903 From a suggestion of _Yalcin Aktar_
%H A089903 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (22,-141,220,-100).
%F A089903 a(n) = s(1, n-1) where s(a, k)=a*(k+1)+a^2*sum(i=0, k, i*10^(k-i))+sum(i=0, k, 5*a*(9*(k-i)+a- 1)*10^(k-i-1)).
%F A089903 a(n) = (-88*(-1+10^n)+9*(16+9*10^n)*n)/162. G.f.: x*(45*x^2+26*x+1) / ((x-1)^2*(10*x-1)^2). - _Colin Barker_, Jun 14 2013
%t A089903 LinearRecurrence[{22,-141,220,-100},{0,1,48,960},20] (* _Harvey P. Dale_, May 12 2023 *)
%Y A089903 Cf. A089904, A089905, A089906, A087330, A089907, A089908, A089909, A034967.
%K A089903 nonn,base,easy
%O A089903 0,3
%A A089903 _Benoit Cloitre_, Nov 14 2003