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Search: id:A111175
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| A111175 |
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Numbers n such that 30*n + 1 is prime. |
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+0
9
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| 1, 2, 5, 6, 7, 8, 9, 11, 14, 18, 19, 20, 21, 22, 23, 25, 27, 33, 34, 35, 39, 40, 41, 43, 44, 46, 49, 51, 54, 58, 60, 61, 62, 65, 67, 71, 72, 74, 75, 76, 77, 78, 79, 84, 85, 89, 91, 93, 95, 99, 100, 102, 104, 106, 109, 110, 111, 112, 113, 117, 118, 119, 121, 123, 131, 134, 135
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Encoded primes with LSD 1 and (SOD-1)/3 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. Example: 2671, with LSD 1 and (SOD-1)/3 = 2 (integer); Then 2671/30 = 89.033, or 89, which is in the sequence, and thus 2671 is prime. [From Ki Punches (ki1212(AT)pocketmail.com), Mar 18 2009]
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FORMULA
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a(n) = (A132230(n) - 1)/30 = Floor[A132230(n)/30]. - Chandler
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EXAMPLE
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If n=99 then 30*n + 1 = 2971 (prime).
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CROSSREFS
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Cf. A158573, A158614, A158648, A158746, A158791, A158806, A158850.
Sequence in context: A039097 A047581 A039067 this_sequence A047326 A039044 A084852
Adjacent sequences: A111172 A111173 A111174 this_sequence A111176 A111177 A111178
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KEYWORD
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nonn
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Oct 21 2005
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 07 2009
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