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 A111575 Powers of 3 repeated four times. 7

%I

%S 1,1,1,1,3,3,3,3,9,9,9,9,27,27,27,27,81,81,81,81,243,243,243,243,729,

%T 729,729,729,2187,2187,2187,2187,6561,6561,6561,6561,19683,19683,

%U 19683,19683,59049,59049,59049,59049,177147,177147,177147,177147,531441

%N Powers of 3 repeated four times.

%C Generating sequence for the number of 0's and 1's (run lengths) in the parity of A006072, A111065 and A118594.

%H Vincenzo Librandi, <a href="/A111575/b111575.txt">Table of n, a(n) for n = 0..8000</a>

%F a(n) = 3^floor(n/4).

%F O.g.f.: -(1+x)*(1+x^2)/(-1+3*x^4). - _R. J. Mathar_, Jan 08 2008

%e a(10) = 3^floor(10/4) = 3^2 = 9.

%t With[{pt=3^Range[0,15]},Sort[Join[pt,pt,pt,pt]]] (* _Harvey P. Dale_, Sep 17 2011 *)

%t Table[PadRight[{},4,3^n],{n,0,15}]//Flatten (* _Harvey P. Dale_, Jan 17 2019 *)

%o (MAGMA) [3^(Floor(n/4)):n in [0..50]]; // _Vincenzo Librandi_, Sep 20 2011

%o (PARI) a(n)=3^(n\4) \\ _Charles R Greathouse IV_, Oct 03 2016

%Y Cf. A006072, A111065, A108411, A118594, A127975.

%K nonn,easy

%O 0,5

%A _Jeremy Gardiner_, Nov 17 2005

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Last modified November 25 11:32 EST 2020. Contains 338623 sequences. (Running on oeis4.)