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%I #12 Sep 08 2022 08:45:59
%S 6,69,699,6999,69999,699999,6999999,69999999,699999999,6999999999,
%T 69999999999,699999999999,6999999999999,69999999999999,
%U 699999999999999,6999999999999999,69999999999999999,699999999999999999
%N 7*10^n-1
%H Vincenzo Librandi, <a href="/A198699/b198699.txt">Table of n, a(n) for n = 0..200</a>
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10)
%F a(n) = 10*a(n-1)+9. a(n) = 11*a(n-1)-10*a(n-2), n>1.
%F G.f. ( 6+3*x ) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Oct 29 2011
%t NestList[10#+9&,6,20] (* or *) LinearRecurrence[{11,-10},{6,69},20] (* _Harvey P. Dale_, Dec 29 2013 *)
%o (Magma) [7*10^n-1: n in [0..30]]
%Y Cf. A002283, A109002.
%K nonn,easy
%O 0,1
%A _Vincenzo Librandi_, Oct 29 2011
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