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%I #18 Sep 08 2022 08:45:48
%S 2,5,5,8,8,11,11,14,14,17,17,20,20,23,23,26,26,29,29,32,32,35,35,38,
%T 38,41,41,44,44,47,47,50,50,53,53,56,56,59,59,62,62,65,65,68,68,71,71,
%U 74,74,77,77,80,80,83,83,86,86,89,89,92,92,95,95,98,98,101,101,104,104,107
%N a(n) = 3*n - a(n-1) + 1 with n > 1, a(1)=2.
%H Vincenzo Librandi, <a href="/A168199/b168199.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F a(n) = (6*n + 5 + 3*(-1)^n)/4. - _Jon E. Schoenfield_, Jun 24 2010
%F G.f.: x*(2-x)*(1+2*x)/((1+x)*(1-x)^2). - _Bruno Berselli_, Feb 28 2012
%t LinearRecurrence[{1, 1, -1}, {2, 5, 5}, 70] (* _Vincenzo Librandi_, Feb 28 2012 *)
%o (Magma) I:=[2, 5, 5]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..40]]; // _Vincenzo Librandi_, Feb 28 2012
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Nov 20 2009
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