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Search: id:A129485
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| A129485 |
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Odd unitary abundant numbers. |
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+0
2
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| 15015, 19635, 21945, 23205, 25935, 26565, 31395, 33495, 33915, 35805, 39585, 41055, 42315, 42735, 45885, 47355, 49665, 50505, 51765, 54285, 55965, 58695, 61215, 64155, 68145, 70455, 72345, 77385, 80535, 82005, 83265, 84315, 91245
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This sequence is different from A112643. The two sequences agree for the first 50 terms but differ thereafter. The exceptions, i.e. those odd unitary abundant numbers that are not squarefree ordinary abundant numbers, are in A129486.
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LINKS
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Eric Weisstein's World of Mathematics, Unitary Divisor.
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FORMULA
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This sequence contains the odd members of A034683. i.e. odd numbers with a positive unitary abundance (A129468).
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EXAMPLE
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The third odd unitary abundant number is 21945. Hence a(3)=21945.
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MATHEMATICA
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UnitaryDivisors[n_Integer?Positive]:=Select[Divisors[n], GCD[ #, n/# ]==1&]; sstar[n_]:=Plus@@UnitaryDivisors[n]-n; Select[Range[1, 10^5, 2], sstar[ # ]># &]
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CROSSREFS
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Cf. A034683, A129486, A034460, A034448, A129487, A002827, A129468, A112643.
Sequence in context: A104875 A046391 A112643 this_sequence A133778 A147578 A151595
Adjacent sequences: A129482 A129483 A129484 this_sequence A129486 A129487 A129488
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KEYWORD
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easy,nonn
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AUTHOR
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Ant King (mathstutoring(AT)ntlworld.com), Apr 17 2007
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