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Search: id:A137532
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| A137532 |
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a(n) = smallest positive integer k such that d(k) = d(k+n) = 2n, where d(m) (A000005) is the number of positive divisors of m, or 0 if no such k exists. |
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+0
2
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| 2, 6, 172, 66, 15952, 84, 22592, 888, 2196, 3750, 459932661
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Comments from Jacques Tramu:
a(12) = ???
a(13) = 5547515219437003248294176693030899
a(17) = 1477350959671318879923111865392957430890479
a(19) > 7907^19 if it exists.
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PROGRAM
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(PARI) lq080419b(n, a)=n*=2; until(0, numdiv(a++)==n|next; numdiv(a+n\2)==n&break); a for(i=1, 99, print1(lq080419b(i)", "))
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CROSSREFS
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Cf. A139416.
Sequence in context: A051240 A003189 A135937 this_sequence A072116 A055696 A091439
Adjacent sequences: A137529 A137530 A137531 this_sequence A137533 A137534 A137535
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KEYWORD
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nonn
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AUTHOR
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Maximilian Hasler (maximilian.hasler(AT)gmail.com), Apr 19 2008
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EXTENSIONS
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a(11) from Jacques Tramu (jacques.tramu(AT)echolalie.com), Apr 20 2008
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