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Search: id:A092965
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| A092965 |
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Greatest prime arising as the product of numbers chosen from among the first n numbers + 1. |
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+0
4
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| 2, 3, 7, 13, 61, 241, 2521, 20161, 72577, 604801, 39916801, 59875201, 3113510401, 17435658241, 186810624001, 10461394944001, 118562476032001, 246245142528001, 24329020081766401, 304112751022080001
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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There are a maximum of 2^n numbers which arise as the products of the subsets of the first n natural numbers. The actual number is smaller because of repetitions. Then a(n) = the greatest prime obtained on adding 1 to each of these numbers.
Different from A089136 (see the comments there).
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LINKS
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Martin Fuller, Table of n, a(n) for n = 1..200
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EXAMPLE
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a(5) = 61 = 3*4*5 + 1. 5! + 1, 4!+ 1, are composite and 2*4*5 + 1 = 41 <61, etc.
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MATHEMATICA
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<<DiscreteMath`; Do[l = Map[Times @@ #&, Subsets[Range[n]]]; Print[Max[Select[Map[ #+1&, l], PrimeQ]]], {n, 1, 20}] (Propper)
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CROSSREFS
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Cf. A060957, A092967.
Sequence in context: A104372 A092969 A089136 this_sequence A051454 A051452 A058017
Adjacent sequences: A092962 A092963 A092964 this_sequence A092966 A092967 A092968
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 26 2004
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)stanford.edu), Aug 13 2005
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