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Search: id:A144856
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| A144856 |
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Semiprimes that are a product of distinct Mersenne primes. |
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+0
3
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| 21, 93, 217, 381, 889, 3937, 24573, 57337, 253921, 393213, 917497, 1040257, 1572861, 3670009, 4063201, 16252897, 16646017, 66584449, 1073602561, 4294434817, 6442450941, 15032385529, 66571993057, 68718821377, 272730423169
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..90
Prime Curios!
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MATHEMATICA
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Mp = 2^{2, 3, 5, 7, 13, 17, 19, 31, 61} - 1; Take[ Union[ Times @@@ Subsets[ Mp, {2}]], 25] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 25 2008]
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CROSSREFS
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Cf. A000668, A001358.
Sequence in context: A065827 A143843 A119109 this_sequence A065522 A123213 A140370
Adjacent sequences: A144853 A144854 A144855 this_sequence A144857 A144858 A144859
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KEYWORD
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nonn
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AUTHOR
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G. L. Honaker, Jr. (honak3r(AT)gmail.com), Sep 22 2008
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EXTENSIONS
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I added the Mathematica coding and extended the sequence. Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 25 2008
More terms from T. D. Noe (noe(AT)sspectra.com), Sep 25 2008
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