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Search: id:A128510
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| A128510 |
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Multiply the sum of the extended factors of a composite by the integer itself to see whether the product is one away from a prime. |
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+0
1
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| 4, 6, 9, 10, 12, 14, 16, 20, 21, 25, 26, 28, 33, 34, 35, 36, 38, 40, 42, 44, 46, 50, 51, 52, 54, 55, 56, 60, 64, 65, 68
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Fifty trials eventuated in 40 primes being one away or splitting a twin. It is curious that the products were all even except for 27, 3*3*3*27=243, and for 63, 3*3*7*63=819. One wonders if an extension would prove this to be the rule.
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REFERENCES
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Similar to A066073.
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FORMULA
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Find the sum of the extended factors of an integer, multiply it by the integer, and see if the product is one away from a prime or splits a twin prime.
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EXAMPLE
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Take 52=2*2*13, having the sum of its factors equaling 2+2+13=17.
Multiply 52 by 17 to get 884, which is one away from prime 883.
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CROSSREFS
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Sequence in context: A010447 A112082 A051278 this_sequence A120329 A123249 A010428
Adjacent sequences: A128507 A128508 A128509 this_sequence A128511 A128512 A128513
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KEYWORD
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nonn,uned
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), May 07 2007
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