%I #13 Aug 20 2023 10:56:31

%S 10,190,1990,19990,199990,1999990,19999990,199999990,1999999990,

%T 19999999990,199999999990,1999999999990,19999999999990,

%U 199999999999990,1999999999999990,19999999999999990,199999999999999990

%N 2*(10^n-5), n>0.

%H Vincenzo Librandi, <a href="/A173813/b173813.txt">Table of n, a(n) for n = 1..100</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11, -10).

%F G.f.: x*(10 + 80*x)/((1 - x)*(1 - 10*x)). - _Vincenzo Librandi_, Aug 20 2014

%t Table[(2 (10^n - 5)), {n, 1, 20}] (* or *) CoefficientList[Series[(10 + 80 x)/((1 - x) (1 - 10 x)), {x, 0, 20}], x] (* _Vincenzo Librandi_, Aug 20 2014 *)

%t LinearRecurrence[{11,-10},{10,190},20] (* _Harvey P. Dale_, Aug 20 2023 *)

%o (Magma) [2*(10^n-5): n in [1..20]]; // _Vincenzo Librandi_, Aug 20 2014

%K nonn

%O 1,1

%A _Vincenzo Librandi_