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A032711
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Numbers n such that the concatenation '2',n,'3' is prime.
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6
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2, 3, 6, 8, 9, 11, 14, 15, 20, 21, 24, 27, 29, 33, 38, 39, 42, 47, 50, 54, 59, 63, 66, 68, 69, 71, 75, 80, 83, 84, 90, 95, 96, 101, 102, 114, 116, 119, 128, 131, 132, 138, 143, 149, 150, 152, 156, 161, 167, 168, 171, 177, 180, 186, 189, 194, 200, 201, 206, 207, 209
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 8 and 21 are in the sequence because 283 and 2213 are primes.
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MAPLE
| v={}; Do[If[PrimeQ[FromDigits[Join[{2}, IntegerDigits[n], {3}]]], v=Append[v, n]], {n, 260}]; v (* *) - Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jun 15 2003
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PROG
| (PARI) for( n=1, 300, isprime(eval(Str(2, n, 3))) & print1(n", ")) \\- M. F. Hasler, Mar 18 2008
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CROSSREFS
| Cf. A083677, A083966, A083969, A092117.
Sequence in context: A013952 A105042 A092114 * A135768 A047244 A111215
Adjacent sequences: A032708 A032709 A032710 * A032712 A032713 A032714
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), May 15 1998
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EXTENSIONS
| Merged with data from duplicate entry A092114. - M. F. Hasler (www.univ-ag.fr/~mhasler), Mar 18 2008
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