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A108114
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Numbers n such that the string 3731n is the decimal expansion of a prime number.
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2
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3, 27, 51, 57, 71, 81, 83, 87, 93, 99, 107, 137, 141, 173, 207, 209, 213, 237, 251, 257, 303, 311, 333, 341, 393, 417, 443, 447, 461, 473, 477, 489, 491, 509, 513, 521, 527, 531, 549, 557, 579, 591, 593, 603, 621, 627, 683, 701, 711, 713, 731, 737, 747, 759
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OFFSET
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1,1
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COMMENTS
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31 and 37 are primes.
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..1000
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EXAMPLE
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3 is in the sequence because 37313 is prime.
99 is in the sequence because 373199 is prime.
207 is in the sequence because 3731207 is prime.
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MAPLE
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a:=proc(n) local z: z:=nops(convert(n, base, 10)): if isprime(3731*10^z+n)=true then n else fi end: seq(a(n), n=1..1000); # Emeric Deutsch, Jul 04 2005
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MATHEMATICA
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Select[Range[1000], PrimeQ[3731*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Aug 26 2013 *)
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PROG
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(Magma) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [1, 3, 7, 3])) ];
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CROSSREFS
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Sequence in context: A175545 A032418 A108163 * A172969 A147267 A071183
Adjacent sequences: A108111 A108112 A108113 * A108115 A108116 A108117
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KEYWORD
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nonn,base
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AUTHOR
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Parthasarathy Nambi, Jun 25 2005
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EXTENSIONS
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More terms from Emeric Deutsch, Jul 04 2005
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STATUS
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approved
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