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%I #22 Sep 08 2022 08:44:38
%S 20,8000,3200000,1280000000,512000000000,204800000000000,
%T 81920000000000000,32768000000000000000,13107200000000000000000,
%U 5242880000000000000000000,2097152000000000000000000000
%N a(n) = 20^(2*n + 1).
%H Vincenzo Librandi, <a href="/A013725/b013725.txt">Table of n, a(n) for n = 0..200</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 (400).
%F From _Philippe Deléham_, Nov 28 2008: (Start)
%F a(n) = 400*a(n-1); a(0)=20.
%F G.f.: 20/(1-400*x). (End)
%p seq(20^(2*n+1),n=0..10); # _Nathaniel Johnston_, Jun 25 2011
%o (Magma) [20^(2*n+1): n in [0..15]]; // _Vincenzo Librandi_, Jun 26 2011
%o (PARI) a(n)=20^(2*n+1) \\ _Charles R Greathouse IV_, Jul 11 2016
%Y Bisection of A009964 (20^n).
%Y Cf. A004171, A013708-A013724, A013726-A013729.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_
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