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Search: id:A127178
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| A127178 |
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Primes whose "Look And Say" descriptions from right to left (in the sense of method B, i.e. digit-indication followed by frequency) are also primes. |
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+0
3
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| 3, 7, 23, 59, 71, 83, 89, 103, 131, 233, 269, 311, 317, 349, 389, 409, 461, 479, 499, 547, 601, 619, 631, 641, 643, 683, 709, 719, 727, 733, 757, 787, 821, 853, 859, 911, 937, 971, 983, 1069, 1093, 1223, 1229, 1231, 1291, 1297, 1327, 1381, 1471, 1489, 1531
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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71, 499, and 1223, for instance, belong to the sequence because their respective descriptions 1171 (1 once, 7 once), 9241 (9 twice, 4 once), 312211 (3 once, 2 twice, 1 once) are all primes.
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MATHEMATICA
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LookAndSayB[ n_] := FromDigits@Flatten@((Through[ {First, Length}[ # ] ] &) /@ Split@Reverse@IntegerDigits@n); Select[Prime@Range[400], PrimeQ@LookAndSayB@# &] (*Chandler*)
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CROSSREFS
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Cf. A022481, A127177, A127179.
Sequence in context: A058000 A002715 A112052 this_sequence A058757 A060089 A106964
Adjacent sequences: A127175 A127176 A127177 this_sequence A127179 A127180 A127181
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KEYWORD
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nonn,base
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AUTHOR
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Lekraj Beedassy (boodhiman (AT)yahoo.com), Jan 07 2007
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EXTENSIONS
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Corrected by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 16 2007
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