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 A086941 #16 May 01 2025 08:32:12
%S A086941 24,294,2994,29994,299994,2999994,29999994,299999994,2999999994,
%T A086941 29999999994,299999999994,2999999999994,29999999999994,
%U A086941 299999999999994,2999999999999994,29999999999999994,299999999999999994,2999999999999999994,29999999999999999994,299999999999999999994
%N A086941 a(n) = k where R(k+6) = 3.
%H A086941 Vincenzo Librandi, <a href="/A086941/b086941.txt">Table of n, a(n) for n = 1..300</a>
%H A086941 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A086941 a(n) = 3*(10^n - 2).
%F A086941 R(a(n)) = A086944(n).
%F A086941 From _Elmo R. Oliveira_, Apr 30 2025: (Start)
%F A086941 G.f.: 6*x*(5*x+4)/((x-1)*(10*x-1)).
%F A086941 E.g.f.: 3*(1 - 2*exp(x) + exp(10*x)).
%F A086941 a(n) = 3*A099150(n).
%F A086941 a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)
%t A086941 3(10^Range[20]-2) (* or *) 10*Table[FromDigits[PadRight[{2},n,9]],{n,20}]+4 (* _Harvey P. Dale_, Jul 25 2023 *)
%o A086941 (Magma) [3*(10^n-2): n in [1..20]]; // _Vincenzo Librandi_, Aug 22 2011
%Y A086941 Cf. A004086, A086944, A099150.
%K A086941 nonn,base,easy
%O A086941 1,1
%A A086941 _Ray Chandler_, Jul 24 2003