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A086942 Integers k such that R(k+8) = 4.

%I A086942 #36 May 02 2025 11:29:32
%S A086942 32,392,3992,39992,399992,3999992,39999992,399999992,3999999992,
%T A086942 39999999992,399999999992,3999999999992,39999999999992,
%U A086942 399999999999992,3999999999999992,39999999999999992,399999999999999992,3999999999999999992,39999999999999999992
%N A086942 Integers k such that R(k+8) = 4.
%H A086942 Vincenzo Librandi, <a href="/A086942/b086942.txt">Table of n, a(n) for n = 1..300</a>
%H A086942 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A086942 a(n) = 4*10^n - 8.
%F A086942 R(a(n)) = A086943(n).
%F A086942 G.f.: 8*x*(5*x+4)/((10*x-1)*(x-1)).
%F A086942 a(n) = 8*A198971(n-1).
%F A086942 From _Elmo R. Oliveira_, May 01 2025: (Start)
%F A086942 E.g.f.: 4*(1 - 2*exp(x) + exp(10*x)).
%F A086942 a(n) = 4*A099150(n) = 2*A086940(n).
%F A086942 a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)
%t A086942 4*10^Range[20] - 8 (* _Paolo Xausa_, Sep 21 2024 *)
%o A086942 (Magma) [4*10^n-8: n in [1..25]]; // _Vincenzo Librandi_, Aug 22 2011
%Y A086942 Cf. A004086, A086940, A086943, A099150, A198971.
%K A086942 nonn,base,easy
%O A086942 1,1
%A A086942 _Ray Chandler_, Jul 24 2003