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Search: id:A158648
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| A158648 |
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Numbers n such that 30*n + 17 is prime. |
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+0
9
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| 0, 1, 3, 4, 5, 6, 7, 8, 10, 11, 15, 18, 19, 20, 21, 22, 26, 27, 28, 29, 31, 32, 36, 39, 40, 42, 43, 45, 47, 49, 53, 54, 55, 56, 59, 61, 62, 63, 66, 67, 69, 73, 74, 75, 76, 78, 80, 81, 82, 88, 89, 92, 94, 96, 97, 98, 104, 105, 108, 111, 113, 115, 117, 118, 120, 122, 125, 126
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Encoded primes with LSD 7 and (SOD-1)/3 non-integer, (LSD, least significant digit; SOD, sum of digits). Divide any such number by 30, if the whole number portion of the quotient is in the sequence, the number is prime.
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FORMULA
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a(n) = (A039949(n) - 17)/30 = Floor[A039949(n)/30]. - Chandler
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EXAMPLE
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Example: 3557, with LSD 7 and (SOD-1)/3 = 6.333 (non-integer); Then 7557/30 = 118.566, or 118 which is in the sequence, and thus 3557 is prime.
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CROSSREFS
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Cf. A111175, A158573, A158614, A158746, A158791, A158806, A158850.
Sequence in context: A026427 A026482 A117346 this_sequence A039078 A073632 A066378
Adjacent sequences: A158645 A158646 A158647 this_sequence A158649 A158650 A158651
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KEYWORD
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nonn
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AUTHOR
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Ki Punches (ki1212(AT)pocketmail.com), Mar 23 2009
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EXTENSIONS
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Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 07 2009
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