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A132171 3^n repeated 3^n times.

%I A132171 #20 Nov 04 2024 17:29:37
%S A132171 1,3,3,3,9,9,9,9,9,9,9,9,9,27,27,27,27,27,27,27,27,27,27,27,27,27,27,
%T A132171 27,27,27,27,27,27,27,27,27,27,27,27,27,81,81,81,81,81,81,81,81,81,81,
%U A132171 81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81,81
%N A132171 3^n repeated 3^n times.
%H A132171 Reinhard Zumkeller, <a href="/A132171/b132171.txt">Table of n, a(n) for n = 0..10000</a>
%F A132171 From _Robert Israel_, Feb 24 2017: (Start)
%F A132171 a(n) = 3^floor(log_3(2n+1)).
%F A132171 a(3*n+1) = a(3*n+2) = a(3*n+3) = 3*a(n).
%F A132171 G.f.: (1-x)^(-1)*Sum_{m>=1} (3^m-3^(m-1))*x^((3^m-1)/2).
%F A132171 (End)
%F A132171 Sum_{n>=0} 1/a(n)^2 = 3/2. - _Amiram Eldar_, Aug 16 2022
%p A132171 seq((3^n)$(3^n),n=0..5); # _Robert Israel_, Feb 24 2017
%t A132171 Table[ConstantArray[3^n, 3^n], {n, 0, 4}] // Flatten (* or *)
%t A132171 Table[3^Floor@ Log[3, 2 n + 1], {n, 0, 81}] (* _Michael De Vlieger_, Feb 24 2017 *)
%o A132171 (Haskell)
%o A132171 import Data.List (transpose)
%o A132171 a132171 n = genericIndex a132171_list n
%o A132171 a132171_list = 1 : zs where
%o A132171    zs = 3 : 3 : 3 : (map (* 3) $ concat $ transpose [zs, zs, zs])
%o A132171 -- _Reinhard Zumkeller_, Sep 01 2015
%o A132171 (Python)
%o A132171 from sympy import integer_log
%o A132171 def A132171(n): return 3**integer_log((n<<1)+1,3)[0] # _Chai Wah Wu_, Nov 04 2024
%Y A132171 Cf. A053644, A132162.
%Y A132171 Cf. A064235, A000244.
%K A132171 nonn
%O A132171 0,2
%A A132171 _Paul Curtz_, Nov 04 2007