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A103630
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Numbers n such that the string 235n is the decimal expansion of a prime number.
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2
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1, 7, 31, 37, 39, 49, 57, 61, 63, 67, 81, 93, 99, 111, 117, 159, 171, 177, 181, 199, 211, 231, 241, 243, 273, 289, 307, 309, 337, 349, 369, 397, 439, 441, 447, 483, 489, 493, 513, 519, 523, 537, 541, 553, 559, 577, 591, 601, 607, 621, 661, 663, 673, 679, 699
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OFFSET
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1,2
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LINKS
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EXAMPLE
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1 is in the sequence because 2351 is prime.
49 is in the sequence because 23549 is prime.
171 is in the sequence because 235171 is prime.
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MAPLE
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map(p->p[2], select(p -> isprime(235*10^p[1]+p[2]), [seq([1, k], k=1..9, 2), seq(seq([d, k], k=10^(d-1)+1..10^d, 2), d=2..3)])); # Robert Israel, Jan 11 2018
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PROG
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(Magma) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [5, 3, 2])) ]; // Klaus Brockhaus, Feb 02 2011
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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