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A371970
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Exponents k such that the binary expansion of 3^k has an even number of ones.
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2
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1, 2, 3, 5, 6, 8, 9, 12, 14, 17, 18, 21, 23, 24, 25, 26, 27, 31, 32, 33, 35, 37, 38, 39, 40, 42, 44, 45, 47, 51, 52, 55, 57, 58, 59, 60, 61, 64, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 96, 99, 102, 104, 105, 106, 109, 112, 116, 127, 131, 132, 133, 134, 135, 136
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OFFSET
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1,2
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LINKS
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MAPLE
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q:= n-> is(add(i, i=Bits[Split](3^n))::even):
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MATHEMATICA
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PROG
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(PARI) is_a371970(k) = hammingweight(3^k)%2 == 0
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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