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Search: id:A089042
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| A089042 |
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Composite numbers such that all divisors >1 have the same number of 1's in binary representation. |
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+0
1
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| 4, 8, 9, 16, 32, 49, 64, 128, 133, 256, 259, 512, 961, 1024, 2048, 2059, 2449, 3713, 4096, 4681, 4867, 6169, 6241, 8192, 8401, 8773, 9353, 10261, 10561, 12307, 12449, 16129, 16384, 16459, 16531, 16771, 18467, 20491, 24649, 24721, 24961, 25217
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A000120(d)=constant for all d with 1<d<=a(n) and d|a(n);
are there terms with more than 2 distinct prime factors?
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EXAMPLE
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Divisors >1 of 259: 7, 37 and 259, which have all three 1's in
binary: 7->'111', 37->'100101' and 259->'100000011', therefore 259 is a
term.
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CROSSREFS
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Cf. A007088, A002808.
Sequence in context: A010417 A155568 A067252 this_sequence A020145 A162898 A071592
Adjacent sequences: A089039 A089040 A089041 this_sequence A089043 A089044 A089045
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 02 2003
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