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A108102
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Numbers n such that the string 1117n is prime.
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0
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1, 3, 7, 21, 31, 33, 51, 67, 73, 79, 81, 91, 99, 111, 117, 153, 169, 177, 199, 243, 247, 253, 267, 273, 279, 301, 307, 309, 321, 349, 367, 379, 433, 439, 451, 463, 471, 477, 481, 483, 489, 513, 549, 553, 579, 591, 601, 603, 607, 609, 657, 661, 673, 679, 681
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Leading zeros in n are not permitted; cases like n=013 relating to the prime 1117013 are not in the sequence.
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EXAMPLE
| n=1 and n=79 are in the sequence because 1117n = 11171 and 1117n=111779 are prime.
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MATHEMATICA
| Select[Range[700], PrimeQ[FromDigits[Join[{1, 1, 1, 7}, IntegerDigits[ #]]]]&] (* From Harvey P. Dale, Sep 13 2011 *)
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PROG
| (MAGMA) [ n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [7, 1, 1, 1])) ]; [From Vincenzo Librandi, Feb 02 2011]
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CROSSREFS
| Cf. A107645, A107644.
Sequence in context: A090504 A018548 A003585 * A065523 A046528 A018572
Adjacent sequences: A108099 A108100 A108101 * A108103 A108104 A108105
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jun 25 2005
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