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Search: id:A112642
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| 6, 255255, 33426748355, 1357656019974967471687377449, 7105630242567996762185122555313528897845637444413640621, 19243446689489980251814895213382305443429535249901228610504118782269091357054548\ 91961917517
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OFFSET
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1,1
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COMMENT
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These numbers are [perhaps the smallest] square-free solutions to the Puzzle 329 of Rivera; a(n) is abundant, not divisible by the first n-1 prime numbers, i.e. the least prime divisor of a(n) is the n-th prime number.
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LINKS
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C. Rivera, Puzzle 329. Odd abundant numbers not divided by 2 or 3.
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FORMULA
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a(n)=A000210[A007684(n)]/A000210(n-1)
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EXAMPLE
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The corresponding sigma[a(n)]/a(n) abundance-ratios are as follows: 2, 2.27462, 2.00097, 2.01433, 2.00101,...;
the terms have 2,3,5,7,11,... as least prime divisors.
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CROSSREFS
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Cf. A000210, A064001, A112640, A007684, A110585, A007684.
Sequence in context: A003834 A152296 A076909 this_sequence A067503 A079288 A072234
Adjacent sequences: A112639 A112640 A112641 this_sequence A112643 A112644 A112645
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 19 2005
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