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Search: id:A067611
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| A067611 |
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Numbers of the form 6xy +- x +- y, where x, y are positive integers. |
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+0
4
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| 4, 6, 8, 9, 11, 13, 14, 15, 16, 19, 20, 21, 22, 24, 26, 27, 28, 29, 31, 34, 35, 36, 37, 39, 41, 42, 43, 44, 46, 48, 49, 50, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, 73, 74, 75, 76, 78, 79, 80, 81, 82, 83, 84, 85, 86, 88, 89, 90, 91, 92, 93, 94
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Equivalently, numbers n such that either 6n-1 or 6n+1 is composite.
Numbers k such that 36k^2-1 is not a product of twin primes. - Artur Jasinski (grafix(AT)csl.pl), Dec 12 2007
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EXAMPLE
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4=6*1*1-1-1. 6=6*1*1+1-1=6*1*1-1+1.
5 cannot be generated by any combination of 6ab+-a+-b.
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MATHEMATICA
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Select[Range[100], !PrimeQ[6#-1]||!PrimeQ[6#+1]&]
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CROSSREFS
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Cf. A002822, A046953, A046954, A070799, A070043.
Cf. A002822, A037074, A136017, A136050.
Adjacent sequences: A067608 A067609 A067610 this_sequence A067612 A067613 A067614
Sequence in context: A137242 A098015 A024887 this_sequence A105803 A138374 A084985
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Feb 01 2002
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 05 2002 and by Dean Hickerson (dean(AT)math.ucdavis.edu), May 07 2002
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