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 A087330 #17 Mar 26 2024 14:46:17
%S A087330 0,15,370,6150,86430,1114210,13641990,161419770,1864197550,
%T A087330 21141975330,236419753110,2614197530890,28641975308670,
%U A087330 311419753086450,3364197530864230,36141975308642010,386419753086419790
%N A087330 Sum of all digits of all integers less than or equal to 555...55 (with n 5's) in base 10.
%C A087330 From a suggestion of _Yalcin Aktar_
%H A087330 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (22,-141,220,-100).
%F A087330 a(n) = 20/9*n-110/81*10^n+110/81+5/2*n*10^n (formula from B. Greco).
%F A087330 G.f.: 5*x*(25*x^2+8*x+3) / ((x-1)^2*(10*x-1)^2). - _Colin Barker_, Jun 14 2013
%e A087330 a(1)=15 since numbers less than or equal to 5 are 1,2,3,4,5 and the sum of digits is 1+2+3+4+5=15.
%t A087330 LinearRecurrence[{22,-141,220,-100},{0,15,370,6150},20] (* _Harvey P. Dale_, Aug 01 2016 *)
%K A087330 base,nonn,easy
%O A087330 0,2
%A A087330 _Benoit Cloitre_, Oct 20 2003