%I #13 Jul 04 2021 02:10:38
%S 15,465,4965,49965,499965,4999965,49999965,499999965,4999999965,
%T 49999999965,499999999965,4999999999965,49999999999965,
%U 499999999999965,4999999999999965,49999999999999965,499999999999999965
%N a(n) = 5*(10^n-7).
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F G.f.: 15*x*(1+20*x) / ( (10*x-1)*(x-1) ). a(n) = 15*A033175(n-1). - _R. J. Mathar_, Jan 05 2011
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_