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A074939 Even numbers such that base 3 representation contains no 2. 5
0, 4, 10, 12, 28, 30, 36, 40, 82, 84, 90, 94, 108, 112, 118, 120, 244, 246, 252, 256, 270, 274, 280, 282, 324, 328, 334, 336, 352, 354, 360, 364, 730, 732, 738, 742, 756, 760, 766, 768, 810, 814, 820, 822, 838, 840, 846, 850, 972, 976, 982, 984, 1000, 1002 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

Sum of an even number of distinct powers of 3. - Emeric Deutsch, Dec 03 2003

LINKS

Table of n, a(n) for n=0..53.

E. Deutsch and B. E. Sagan, Congruences for Catalan and Motzkin numbers and related sequences, arXiv:math/0407326 [math.CO], 2004.

E. Deutsch and B. E. Sagan, Congruences for Catalan and Motzkin numbers and related sequences, J. Num. Theory 117 (2006), 191-215.

FORMULA

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)).

a(n) + A074938(n) = A055246(n+1). - Philippe Deléham, Jul 10 2005

MATHEMATICA

Select[2*Range[0, 600], DigitCount[#, 3, 2]==0&] (* Harvey P. Dale, Dec 10 2016 *)

CROSSREFS

Cf. A006996, A010060, A074938, A083095.

Sequence in context: A050868 A007319 A175436 * A038464 A125966 A259725

Adjacent sequences:  A074936 A074937 A074938 * A074940 A074941 A074942

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Oct 04 2002; Nov 15 2003

STATUS

approved

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Last modified March 3 14:58 EST 2021. Contains 341762 sequences. (Running on oeis4.)