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Search: id:A130676
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| A130676 |
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Let '+/-' mean 'may be either added or subtracted.' By examining expressions of the form 2x4 +/- 3, 6x8 +/- 5, 10x12 +/- 7, and so forth, we see that primes result. The sequence lists the n's of the formulas given below. |
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 15, 16, 17, 18, 20, 22, 23, 25
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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If the odd number is added, 16xn^2 - 6n + 1 generates primes. If the odd number is subtracted, 16xn^2 - 10n - 1 generates the primes.
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EXAMPLE
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For n=20, 16 x 20^2 - 10x20 - 1= 6199, which is prime. This is the
same as 78x80-41. For the odd number added for n=15, 16 x 15^2 - 6x15 +1=3511,
which is prime. This is the equivalent of 58x60 + 31.
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CROSSREFS
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Sequence in context: A132018 A044919 A011871 this_sequence A039227 A039273 A039164
Adjacent sequences: A130673 A130674 A130675 this_sequence A130677 A130678 A130679
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KEYWORD
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easy,nonn,uned
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), Jun 28 2007
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