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Search: id:A125839
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| A125839 |
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a(n) is the smallest number m such that k*m - 1 is prime for all k=3,4,...,n. |
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5
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| 1, 1, 6, 18, 120, 1260, 1485540, 28667100, 28667100, 842889105240, 2747586810150
(list; graph; listen)
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OFFSET
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3,3
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COMMENT
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For n > 6, 10 divides a(n). a(12)-a(13) from Farideh Firoozbakht (mymontain(AT)yahoo.com).
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LINKS
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Carlos Rivera, Problems & puzzles.
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EXAMPLE
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a(11)=28667100 because 3*28667100-1, 4*28667100-1, 5*28667100-1, 6*28667100-1, 7*28667100-1, 8*28667100-1, 9*28667100-1, 10*28667100-1 & 11*28667100-1 are prime and 28667100 is the smallest number with this property.
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CROSSREFS
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Cf. A125838, A088651, A088250.
Sequence in context: A007126 A009576 A009580 this_sequence A117813 A012758 A003496
Adjacent sequences: A125836 A125837 A125838 this_sequence A125840 A125841 A125842
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KEYWORD
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hard,more,nonn
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AUTHOR
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Luke Pebody (luke.pebody(AT)gmail.com), Jan 02 2007
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