|
%I #11 Sep 08 2022 08:45:48
%S 1,6,3,18,9,54,27,162,81,486,243,1458,729,4374,2187,13122,6561,39366,
%T 19683,118098,59049,354294,177147,1062882,531441,3188646,1594323,
%U 9565938,4782969,28697814,14348907,86093442,43046721,258280326
%N a(n) = 3*a(n-2) for n > 2; a(1) = 1, a(2) = 6.
%C Interleaving of A000244 and 6*A000244.
%C Second binomial transform is A055845. Sixth binomial transform is A153597.
%H Vincenzo Librandi, <a href="/A166450/b166450.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) = (3+(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2.
%F G.f.: x*(1+6*x)/(1-3*x^2).
%t LinearRecurrence[{0,3},{1,6}, 50] (* _G. C. Greubel_, May 14 2016 *)
%o (Magma) [ n le 2 select 5*n-4 else 3*Self(n-2): n in [1..35] ];
%Y Cf. A000244 (powers of 3), A055845, A153597.
%K nonn,easy
%O 1,2
%A _Klaus Brockhaus_, Oct 13 2009
|
