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A159481
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Number of evil numbers <= n, see A001969.
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8
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1, 1, 1, 2, 2, 3, 4, 4, 4, 5, 6, 6, 7, 7, 7, 8, 8, 9, 10, 10, 11, 11, 11, 12, 13, 13, 13, 14, 14, 15, 16, 16, 16, 17, 18, 18, 19, 19, 19, 20, 21, 21, 21, 22, 22, 23, 24, 24, 25, 25, 25, 26, 26, 27, 28, 28, 28, 29, 30, 30, 31, 31, 31, 32, 32, 33, 34, 34, 35, 35, 35, 36, 37, 37, 37
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OFFSET
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0,4
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COMMENTS
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Limit_{n->oo} n/a(n) = 1/2.
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LINKS
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FORMULA
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G.f.: (1/(1 - x)^2 + Product_{k>=1} (1 - x^(2^k)))/2. - Ilya Gutkovskiy, Apr 03 2019
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EXAMPLE
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a(10) = #{0,11,101,110,1001,1010} = #{0,3,5,6,9,10} = 6.
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MATHEMATICA
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Accumulate[Table[If[EvenQ[DigitCount[n, 2, 1]], 1, 0], {n, 0, 80}]] (* Harvey P. Dale, Mar 19 2018 *)
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PROG
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(Python)
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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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