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%I #8 Sep 08 2022 08:45:48
%S 1,5,3,15,9,45,27,135,81,405,243,1215,729,3645,2187,10935,6561,32805,
%T 19683,98415,59049,295245,177147,885735,531441,2657205,1594323,
%U 7971615,4782969,23914845,14348907,71744535,43046721,215233605,129140163
%N a(n) = 3*a(n-2) for n > 2; a(1) = 1, a(2) = 5.
%C Interleaving of A000244 and A005030.
%C Second binomial transform is A054485. Fifth binomial transform is A153596.
%H Vincenzo Librandi, <a href="/A166465/b166465.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0, 3).
%F a(n) = (4+(-1)^n)*3^(1/4*(2*n-5+(-1)^n)).
%F G.f.: x*(1+5*x)/(1-3*x^2).
%o (Magma) [ n le 2 select 4*n-3 else 3*Self(n-2): n in [1..35] ];
%Y Equals A162813 preceded by 1.
%Y Cf. A000244 (powers of 3), A005030 (5*3^n), A054485, A153596.
%K nonn,easy
%O 1,2
%A _Klaus Brockhaus_, Oct 14 2009
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