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Search: id:A060658
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| A060658 |
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Sigma(x) has no even solution n. |
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+0
1
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| 2, 10, 16, 22, 26, 34, 46, 50, 52, 58, 64, 66, 70, 76, 82, 86, 88, 92, 94, 100, 106, 116, 118, 122, 130, 134, 136, 142, 146, 148, 154, 166, 170, 172, 178, 184, 188, 190, 196, 202, 206, 208, 214, 218, 220, 226, 232, 236, 238, 244, 246, 250, 254, 262, 268, 274
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OFFSET
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1,1
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EXAMPLE
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a(2) = 10 because there is no x < 10 whose sigma(x) = 10, an even number.
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MATHEMATICA
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a = {}; Do[ s = DivisorSigma[ 1, n ]; If[ EvenQ[ s ], a = Append[ a, s ] ], {n, 1, 400} ]; Complement[ Table[ 2n, {n, 1, 200} ], Union[ a ] ]
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CROSSREFS
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Cf. A007369.
Sequence in context: A043429 A105041 A138632 this_sequence A054028 A063716 A125212
Adjacent sequences: A060655 A060656 A060657 this_sequence A060659 A060660 A060661
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 18 2001
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