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A107644
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Numbers n such that the string 1113n is the decimal expansion of a prime number.
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4
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1, 17, 23, 37, 41, 47, 73, 103, 137, 149, 157, 173, 181, 187, 193, 197, 199, 221, 239, 253, 257, 317, 319, 337, 349, 373, 379, 401, 403, 421, 451, 461, 481, 491, 509, 521, 527, 557, 569, 587, 599, 617, 643, 667, 701, 703, 713, 719, 751, 773, 781, 787, 793
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| 11 and 13 are twin primes.
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EXAMPLE
| n=1: 11131 is prime.
n=47: 111347 is prime.
n=149: 1113149 is prime.
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PROG
| (MAGMA) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [3, 1, 1, 1])) ];
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CROSSREFS
| Sequence in context: A080830 A165566 A072184 * A158710 A156567 A139843
Adjacent sequences: A107641 A107642 A107643 * A107645 A107646 A107647
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jun 09 2005
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