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Search: id:A036896
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| A036896 |
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Odd refactorable numbers. |
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+0
7
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| 1, 9, 225, 441, 625, 1089, 1521, 2025, 2601, 3249, 4761, 5625, 6561, 7569, 8649, 12321, 15129, 16641, 19881, 25281, 31329, 33489, 35721, 40401, 45369, 47961, 50625, 56169, 62001, 71289, 84681, 91809, 95481, 99225, 103041, 106929, 114921
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Odd refactorable numbers are always squares.
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LINKS
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S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.
S. Colton, HR - Automatic Theory Formation in Pure Mathematics
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EXAMPLE
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9 is refactorable because tau(9)=3 and 3 divides 9.
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MATHEMATICA
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Do[If[IntegerQ[n/DivisorSigma[0, n]], Print[n]], {n, 1, 100000, 2}]
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CROSSREFS
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Cf. A033950.
Adjacent sequences: A036893 A036894 A036895 this_sequence A036897 A036898 A036899
Sequence in context: A079913 A033632 A110260 this_sequence A120319 A057530 A014736
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KEYWORD
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nonn
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AUTHOR
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Simon Colton (simonco(AT)cs.york.ac.uk)
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