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a(n) = 3*6^n.
6

%I #12 Sep 08 2022 08:45:49

%S 3,18,108,648,3888,23328,139968,839808,5038848,30233088,181398528,

%T 1088391168,6530347008,39182082048,235092492288,1410554953728,

%U 8463329722368,50779978334208,304679870005248,1828079220031488

%N a(n) = 3*6^n.

%C a(n) = A081341(n+1).

%C Essentially first differences of A125682.

%C Binomial transform of A005053 without initial term 1.

%C Second binomial transform of A164346.

%C Inverse binomial transform of A169634.

%C Second inverse binomial transform of A103333 without initial term 1.

%C Contribution from _Reinhard Zumkeller_, May 02 2010: (Start)

%C a(n) = 3*A000400(n) = A000400(n+1)/2;

%C subsequence of A003586; a(n)=A003586(A014105(n)) for n<6. (End)

%H Vincenzo Librandi, <a href="/A169604/b169604.txt">Table of n, a(n) for n = 0..300</a>

%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (6).

%F a(n) = 6*a(n-1) for n > 0; a(0) = 3.

%F G.f.: 3/(1-6*x).

%o (Magma) [ 3*6^n: n in [0..19] ];

%o (PARI) a(n)=3*6^n \\ _Charles R Greathouse IV_, Oct 16 2015

%Y Cf. A081341, A125682 ((6^n-1)*3/5), A005053 (expand (1-2x)/(1-5x)), A164346 (3*4^n), A169634 (3*7^n), A103333 (expand (1-5x)/(1-8x)).

%K nonn,easy

%O 0,1

%A _Klaus Brockhaus_, Apr 04 2010