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Search: id:A107642
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| A107642 |
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Numbers n such that the string 57n is prime. |
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+0
1
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| 1, 7, 11, 17, 37, 41, 43, 49, 79, 83, 91, 107, 119, 131, 139, 143, 149, 163, 173, 179, 191, 193, 203, 221, 223, 241, 251, 259, 269, 271, 283, 287, 301, 329, 331, 347, 349, 367, 373, 383, 389, 397, 413, 427, 457, 467, 487, 493, 503, 527, 529, 557, 559, 571, 587
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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5 and 7 are twin primes.
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EXAMPLE
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If n=1, then 57n = 571 (prime).
If n=41, then 57n = 5741 (prime).
If n=83, then 57n = 5783 (prime).
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PROGRAM
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(PARI) for(n=1, 1000, if(isprime(eval(concat("57", n))), print1(n, ", "))) (Shepherd)
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CROSSREFS
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Adjacent sequences: A107639 A107640 A107641 this_sequence A107643 A107644 A107645
Sequence in context: A078725 A019418 A068674 this_sequence A134572 A079651 A097956
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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), Jun 09 2005
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EXTENSIONS
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More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 13 2005
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