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A074939 Even numbers such that base 3 representation contains no 2. 5

%I

%S 0,4,10,12,28,30,36,40,82,84,90,94,108,112,118,120,244,246,252,256,

%T 270,274,280,282,324,328,334,336,352,354,360,364,730,732,738,742,756,

%U 760,766,768,810,814,820,822,838,840,846,850,972,976,982,984,1000,1002

%N Even numbers such that base 3 representation contains no 2.

%C Even numbers in A005836; n such that binomial(2n,n) == 1 (mod 3).

%C Sum of an even number of distinct powers of 3. - _Emeric Deutsch_, Dec 03 2003

%H E. Deutsch and B. E. Sagan, <a href="https://arxiv.org/abs/math/0407326">Congruences for Catalan and Motzkin numbers and related sequences</a>, arXiv:math/0407326 [math.CO], 2004.

%H E. Deutsch and B. E. Sagan, <a href="https://doi.org/10.1016/j.jnt.2005.06.005">Congruences for Catalan and Motzkin numbers and related sequences</a>, J. Num. Theory 117 (2006), 191-215.

%F a(n) = A083094(n)/2; a(n) mod 3 = A010060(n); n such that coefficient of x^n equals 1 in Product_{k>=0} (1 - x^(3^k)).

%F a(n) + A074938(n) = A055246(n+1). - _Philippe Deléham_, Jul 10 2005

%t Select[2*Range[0,600],DigitCount[#,3,2]==0&] (* _Harvey P. Dale_, Dec 10 2016 *)

%Y Cf. A006996, A010060, A074938, A083095.

%K easy,nonn

%O 0,2

%A _Benoit Cloitre_, Oct 04 2002; Nov 15 2003

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Last modified April 13 11:56 EDT 2021. Contains 342936 sequences. (Running on oeis4.)