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Search: id:A090329
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| A090329 |
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Number of divisors of n that are prefixes of other divisors of n in binary representation. |
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+0
2
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| 0, 1, 1, 2, 1, 2, 1, 3, 1, 3, 1, 4, 1, 2, 2, 4, 1, 4, 1, 4, 2, 3, 1, 6, 1, 2, 2, 4, 1, 5, 1, 5, 1, 3, 1, 7, 1, 3, 2, 6, 1, 5, 1, 4, 3, 3, 1, 8, 1, 4, 2, 4, 1, 6, 2, 6, 2, 2, 1, 8, 1, 2, 3, 6, 1, 5, 1, 5, 1, 5, 1, 9, 1, 3, 2, 5, 1, 6, 1, 8, 2, 3, 1, 8, 2, 3, 2, 6, 1, 7, 1, 4, 2, 3, 2, 10, 1, 3, 2, 6, 1, 6
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OFFSET
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1,4
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COMMENT
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a(p) = 1 for all primes p;
a(n) = A090330(n) + 1.
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EXAMPLE
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Divisors of n=35: {1,5,7,35}, in binary {1,101,111,100011}: as
only '1' is a prefex, a(35)=1;
divisors of n=45: {1,3,5,9,15,45}, in binary
{1,11,101,1001,1111,101101}: '1' is a prefex of all other divisors, '11' of
'1111' and '101' of '101101', therefore a(45)=3.
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CROSSREFS
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Cf. A000005.
Sequence in context: A077767 A137163 A072625 this_sequence A027353 A027352 A029238
Adjacent sequences: A090326 A090327 A090328 this_sequence A090330 A090331 A090332
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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), Nov 26 2003
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