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Search: id:A108227
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| A108227 |
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a(n) is the least number of prime factors for any abundant number with p_n (the n-th prime) as its least factor. |
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+0
1
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| 3, 5, 9, 18, 31, 46, 67, 91, 122, 157, 194, 238, 284, 334, 392, 455, 522, 591, 668, 748, 834, 929, 1028, 1133, 1241, 1352, 1469, 1594, 1727, 1869, 2019, 2163, 2315, 2471, 2636, 2802, 2977, 3156, 3341, 3534, 3731, 3933, 4145, 4358, 4581, 4811
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If we replace "abundant" in the definition with "non-deficient", we get the same sequence with an initial 2 instead of 3, barring an astronomically unlikely coincidence with some as-yet-undiscovered odd perfect number
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EXAMPLE
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a(2) = 5 since 945 = 3^3.5.7 is an abundant number with p_2 = 3 as its smallest prime factor and no such number exists with fewer than 5 prime factors
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CROSSREFS
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Cf. A000040, A005101, A006038, A001222.
Cf. A107705. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 24 2008]
Sequence in context: A062221 A074861 A120941 this_sequence A028411 A018098 A108859
Adjacent sequences: A108224 A108225 A108226 this_sequence A108228 A108229 A108230
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KEYWORD
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nonn
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AUTHOR
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hv(AT)crypt.org (Hugo van der Sanden), Jun 17 2005
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