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 A177074 #23 Sep 08 2022 08:45:53
%S A177074 15,285,2985,29985,299985,2999985,29999985,299999985,2999999985,
%T A177074 29999999985,299999999985,2999999999985,29999999999985,
%U A177074 299999999999985,2999999999999985,29999999999999985,299999999999999985
%N A177074 3*(10^n-5).
%C A177074 Apparently 15 times the entries in A067272. - _R. J. Mathar_, Aug 24 2011
%H A177074 Vincenzo Librandi, <a href="/A177074/b177074.txt">Table of n, a(n) for n = 1..100</a>
%H A177074 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A177074 G.f. 15*x*(1+8*x) / ( (10*x-1)*(x-1) ). - _R. J. Mathar_, Aug 24 2011
%F A177074 a(n) = 11*a(n-1) - 10*a(n-2), n>1. - _Vincenzo Librandi_, Apr 26 2014
%t A177074 Table[3*(10^n-5),{n,20}] (* or *) LinearRecurrence[{11,-10},{15,285},20] (* _Harvey P. Dale_, Apr 25 2014 *)
%t A177074 CoefficientList[Series[15 (1 + 8 x)/((10 x - 1) (x - 1)), {x, 0, 40}], x] (* _Vincenzo Librandi_, Apr 26 2014 *)
%o A177074 (Magma) [3*(10^n-5): n in [1..20]]; // _Vincenzo Librandi_, Apr 26 2014
%K A177074 nonn,easy
%O A177074 1,1
%A A177074 _Vincenzo Librandi_