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Search: id:A023237
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| A023237 |
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Numbers n such that n and 10n + 1 are both prime. |
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+0
3
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| 3, 7, 13, 19, 31, 43, 97, 103, 109, 151, 157, 181, 193, 211, 241, 271, 337, 349, 367, 409, 421, 439, 487, 523, 547, 571, 601, 613, 631, 691, 733, 769, 811, 823, 829, 883, 937, 1009, 1021, 1033, 1039, 1063, 1069, 1117, 1201, 1249, 1279, 1291, 1459, 1483, 1489
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Primes which with a 1 appended stay prime.
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MAPLE
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with(numtheory); for i from 1 to 500 do if isprime(10*ithprime(i)+1) then printf(`%d, `, ithprime(i)) fi: od: (James A. Sellers, (sellersj(AT)math.psu.edu), Apr 09 2005)
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MATHEMATICA
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Select[ Prime[ Range[ 240]], PrimeQ[ FromDigits[ Join[ IntegerDigits[ # ], {1}]]] &] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005)
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CROSSREFS
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Cf. A105435.
Sequence in context: A023205 A103521 A103966 this_sequence A106061 A155703 A023217
Adjacent sequences: A023234 A023235 A023236 this_sequence A023238 A023239 A023240
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KEYWORD
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nonn
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AUTHOR
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David W. Wilson (davidwwilson(AT)comcast.net)
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com) at the suggestion of M. F. Hasler, Aug 24 2007
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