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%I #17 Mar 15 2023 14:16:37
%S 3,19,99,499,2499,12499,62499,312499,1562499,7812499,39062499,
%T 195312499,976562499,4882812499,24414062499,122070312499,610351562499,
%U 3051757812499,15258789062499,76293945312499,381469726562499,1907348632812499
%N a(n) = 4*5^n-1.
%H Vincenzo Librandi, <a href="/A198763/b198763.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,-5).
%F a(n) = 5*a(n-1)+4.
%F a(n) = 6*a(n-1)-5*a(n-2), n>1.
%F G.f.: (3 + x)/(1 - 6*x + 5*x^2). - _Vincenzo Librandi_, Jan 04 2013
%t CoefficientList[Series[(3 + x)/(1 - 6*x + 5*x^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 04 2013 *)
%t NestList[5#+4&,3,30] (* or *) LinearRecurrence[{6,-5},{3,19},30] (* _Harvey P. Dale_, Jul 03 2021 *)
%o (Magma) [4*5^n-1: n in [0..30]]
%Y Cf. A024049, A057651, A081655.
%K nonn,easy
%O 0,1
%A _Vincenzo Librandi_, Oct 30 2011