cp's OEIS Frontend

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.

%I A127178 #13 Jul 22 2017 08:33:00
%S A127178 3,7,23,59,71,83,89,103,131,233,269,311,317,349,389,409,461,479,499,
%T A127178 547,601,619,631,641,643,683,709,719,727,733,757,787,821,853,859,911,
%U A127178 937,971,983,1069,1093,1223,1229,1231,1291,1297,1327,1381,1471,1489,1531
%N 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.
%e A127178 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.
%t A127178 LookAndSayB[ n_] := FromDigits@Flatten@((Through[ {First, Length}[ # ] ] &) /@ Split@Reverse@IntegerDigits@n); Select[Prime@Range[400],PrimeQ@LookAndSayB@# &] (* _Ray Chandler_, Jan 16 2007 *)
%Y A127178 Cf. A022481, A127177, A127179.
%K A127178 nonn,base
%O A127178 1,1
%A A127178 _Lekraj Beedassy_, Jan 07 2007
%E A127178 Corrected by _Ray Chandler_, Jan 16 2007