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 A086946 #24 May 02 2025 12:52:39 %S A086946 14,194,1994,19994,199994,1999994,19999994,199999994,1999999994, %T A086946 19999999994,199999999994,1999999999994,19999999999994, %U A086946 199999999999994,1999999999999994,19999999999999994,199999999999999994,1999999999999999994,19999999999999999994,199999999999999999994 %N A086946 Numbers k such that R(k+6) = 2. %H A086946 Vincenzo Librandi, <a href="/A086946/b086946.txt">Table of n, a(n) for n = 1..300</a> %H A086946 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10). %F A086946 a(n) = 2*(10^n - 3). %F A086946 R(a(n)) = A086949(n). %F A086946 From _Stefano Spezia_, Dec 15 2022: (Start) %F A086946 O.g.f.: 2*x*(7 + 20*x)/((1 - x)*(1 - 10*x)). %F A086946 E.g.f.: 2*(2 - 3*exp(x) + exp(10*x)). %F A086946 a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End) %F A086946 a(n) = 2*A173833(n). - _Elmo R. Oliveira_, May 02 2025 %o A086946 (Magma) [2*(10^n-3): n in [1..25] ]; // _Vincenzo Librandi_, Aug 22 2011 %Y A086946 Cf. A004086, A086949, A173833. %K A086946 nonn,base,easy %O A086946 1,1 %A A086946 _Ray Chandler_, Jul 24 2003