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A105402
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Positive integers k such that the prime factors of sigma(k) are a subset of the prime factors of k.
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5
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1, 6, 28, 30, 42, 66, 84, 102, 120, 138, 186, 210, 270, 282, 318, 330, 364, 420, 426, 462, 496, 510, 546, 570, 642, 672, 690, 714, 762, 840, 868, 870, 924, 930, 966, 1080, 1092, 1122, 1146, 1302, 1320, 1410, 1428, 1488, 1518, 1590, 1638, 1722, 1770, 1782, 1890
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OFFSET
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1,2
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COMMENTS
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Pollack and Pomerance call these numbers "prime-deficient numbers". - Amiram Eldar, Jun 02 2020
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LINKS
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Paul Pollack and Carl Pomerance, Prime-Perfect Numbers, INTEGERS, Electronic J. of Combinatorial Number Theory, Vol. 12a, Paper A14, 2012.
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EXAMPLE
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102 is a term since 102 = 2*3*17 and sigma(102) = 2^3*3^3.
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MAPLE
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A:=select(proc(z) numtheory[factorset](sigma(z)) subset numtheory[factorset](z) end, [$1..100000]); has 716 members.
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MATHEMATICA
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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