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 A177097 #15 Sep 13 2022 10:50:49
%S A177097 30,570,5970,59970,599970,5999970,59999970,599999970,5999999970,
%T A177097 59999999970,599999999970,5999999999970,59999999999970,
%U A177097 599999999999970,5999999999999970,59999999999999970,599999999999999970
%N A177097 a(n) = 6*(10^n-5).
%C A177097 Apparently 30 times the entries of A067272. - _R. J. Mathar_, Aug 24 2011
%H A177097 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A177097 G.f.: 30*x*(1+8*x) / ( (10*x-1)*(x-1) ). - _R. J. Mathar_, Aug 24 2011
%F A177097 a(1)=30, a(2)=570, a(n)=11*a(n-1)-10*a(n-2). [_Harvey P. Dale_, Oct 10 2011]
%t A177097 Join[{30,570},FromDigits/@(Join[{5},#,{7,0}]&/@Table[PadLeft[{},n,9], {n,20}])] (* or *) LinearRecurrence[{11,-10},{30,570},20] (* _Harvey P. Dale_, Oct 10 2011 *)
%Y A177097 Cf. A067272.
%K A177097 nonn,easy
%O A177097 1,1
%A A177097 _Vincenzo Librandi_