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A217373
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Numbers n the representation of which in base 3 ends in 2*k or 2*k+1 zeros, where k is odd.
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1
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9, 18, 27, 36, 45, 54, 63, 72, 90, 99, 108, 117, 126, 135, 144, 153, 171, 180, 189, 198, 207, 216, 225, 234, 252, 261, 270, 279, 288, 297, 306, 315, 333, 342, 351, 360, 369, 378, 387, 396, 414, 423, 432, 441, 450, 459, 468, 477, 495, 504, 513, 522, 531, 540
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OFFSET
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1,1
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COMMENTS
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Or numbers having infinitary divisor 9, or the same having factor 9 in their Fermi-Dirac factorization as product of distinct terms of A050376.
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LINKS
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FORMULA
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a(n)/(10*n) tends to 1, as n goes to infinity.
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MATHEMATICA
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Select[Map[# Boole[IntegerQ[(1/4 (1+#))]||IntegerQ[(1/4 (2+#))]&[Length[Last[Split[IntegerDigits[#, 3]]]]]]&, Range[3, 5000, 3]], #>0&] (* Peter J. C. Moses, Mar 20 2013 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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