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%I #23 Sep 08 2022 08:44:38
%S 9,729,59049,4782969,387420489,31381059609,2541865828329,
%T 205891132094649,16677181699666569,1350851717672992089,
%U 109418989131512359209,8862938119652501095929,717897987691852588770249,58149737003040059690390169
%N a(n) = 9^(2*n + 1).
%H Vincenzo Librandi, <a href="/A013714/b013714.txt">Table of n, a(n) for n = 0..150</a>
%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (81).
%F From _Philippe Deléham_, Nov 25 2008: (Start)
%F a(n) = 81*a(n-1); a(0)=9.
%F G.f.: 9/(1-81*x). (End)
%t 9^(2*Range[0,20]+1) (* or *) NestList[81#&,9,20] (* _Harvey P. Dale_, May 25 2020 *)
%o (Magma) [9^(2*n+1): n in [0..20]]; // _Vincenzo Librandi_, May 26 2011
%o (PARI) a(n)=9^(2*n+1) \\ _Charles R Greathouse IV_, Jul 11 2016
%Y Cf. A001019.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_
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