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Search: id:A107705
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| A107705 |
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a(n) is the least number of prime factors in any non-deficient number that has the n-th prime as its least prime factor. |
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+0
2
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| 2, 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, 5053, 5293
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OFFSET
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1,1
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COMMENT
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Barring unforeseen odd perfect numbers (which it has been proved must have at least 29 prime factors if they exist at all), if we replace "non-deficient" in the description with "abundant", the value of a(1) becomes 3 and all other values stay the same.
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EXAMPLE
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a(2) is 5 since 1) there are abundant numbers with a(2)=5 prime factors of which p_2=3 is the least prime factor (such as 945 = 3^3.5.7); 2) there are no non-deficient numbers with fewer than 5 prime factors, of which 3 is the least prime factor.
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CROSSREFS
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Cf. A000040, A023196, A005101, A001222.
Sequence in context: A019135 A069957 A091356 this_sequence A002883 A077865 A117353
Adjacent sequences: A107702 A107703 A107704 this_sequence A107706 A107707 A107708
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KEYWORD
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nonn
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AUTHOR
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Hugo van der Sanden (hv(AT)crypt.org), Jun 10 2005
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