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Search: id:A127177
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| A127177 |
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Primes whose "Look And Say" descriptions from right to left (in the sense of method A, i.e. frequency followed by digit-indication) are also primes. |
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3
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| 3, 7, 71, 103, 113, 163, 173, 311, 313, 331, 337, 349, 373, 757, 773, 797, 919, 953, 977, 991, 1109, 1123, 1151, 1171, 1181, 1213, 1237, 1277, 1279, 1297, 1327, 1423, 1447, 1543, 1553, 1567, 1621, 1663, 1669, 1747, 1811, 1873, 1877, 1889, 1993, 1999, 3049
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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71, 331, and 1277, for instance, belong to the sequence because their respective descriptions 1171 (one 1, one 7), 1123 (one 1, two 3's) and 271211 (two 7's, one 2, one 1) are primes.
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MATHEMATICA
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LookAndSayA[ n_] := FromDigits@Flatten@((Through[ {Length, First}[ # ] ] &) /@ Split@Reverse@IntegerDigits@n); Select[Prime@Range[450], PrimeQ@LookAndSayA@# &] (*Chandler*)
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CROSSREFS
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Cf. A006711, A127178, A127179.
Sequence in context: A041817 A120364 A088797 this_sequence A127179 A113841 A128072
Adjacent sequences: A127174 A127175 A127176 this_sequence A127178 A127179 A127180
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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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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 16 2007
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