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A100008
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Number of unitary divisors of 2n.
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0
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2, 2, 4, 2, 4, 4, 4, 2, 4, 4, 4, 4, 4, 4, 8, 2, 4, 4, 4, 4, 8, 4, 4, 4, 4, 4, 4, 4, 4, 8, 4, 2, 8, 4, 8, 4, 4, 4, 8, 4, 4, 8, 4, 4, 8, 4, 4, 4, 4, 4, 8, 4, 4, 4, 8, 4, 8, 4, 4, 8, 4, 4, 8, 2, 8, 8, 4, 4, 8, 8, 4, 4, 4, 4, 8, 4, 8, 8, 4, 4, 4, 4, 4, 8, 8, 4, 8, 4, 4, 8, 8, 4, 8, 4, 8, 4, 4, 4, 8, 4, 4, 8, 4, 4, 16
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| b(n) = a(n)/a(1) is multiplicative with b(2^e) = 1, b(p^e) = 2 otherwise. David W. Wilson (davidwwilson(AT)comcast.net) Jun 12, 2005.
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EXAMPLE
| a(6)=4 because among the six divisors of 12 only 1,3,4 and 12 are unitary.
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MAPLE
| with(numtheory): for n from 1 to 120 do printf(`%d, `, 2^nops(ifactors(2*n)[2])) od: (Deutsch)
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CROSSREFS
| Bisection of A034444.
Sequence in context: A152858 A091248 A082991 * A102763 A054844 A057936
Adjacent sequences: A100005 A100006 A100007 * A100009 A100010 A100011
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 20 2004
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 24 2004
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