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%I #21 Sep 08 2022 08:46:00
%S 3,39,399,3999,39999,399999,3999999,39999999,399999999,3999999999,
%T 39999999999,399999999999,3999999999999,39999999999999,
%U 399999999999999,3999999999999999,39999999999999999,399999999999999999,3999999999999999999
%N a(n) = 4*10^n-1.
%H Vincenzo Librandi, <a href="/A198970/b198970.txt">Table of n, a(n) for n = 0..200</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F a(n) = 3*A097166(n).
%F a(n) = 10*a(n-1)+9, n>0.
%F a(n) = 11*a(n-1)-10*a(n-2), n>1.
%F G.f.: 3*(1 + 2*x)/(1 - 11*x + 10*x^2). - _Vincenzo Librandi_, Jan 03 2013
%t CoefficientList[Series[3*(1 + 2*x)/(1 - 11*x + 10*x^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 03 2013 *)
%o (Magma) [4*10^n-1 : n in [0..20]]
%K nonn,easy
%O 0,1
%A _Vincenzo Librandi_, Nov 01 2011
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