A127178 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.
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
Offset: 1
Examples
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.
Programs
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Mathematica
LookAndSayB[ n_] := FromDigits@Flatten@((Through[ {First, Length}[ # ] ] &) /@ Split@Reverse@IntegerDigits@n); Select[Prime@Range[400],PrimeQ@LookAndSayB@# &] (* Ray Chandler, Jan 16 2007 *)
Extensions
Corrected by Ray Chandler, Jan 16 2007