A127177 -id:A127177 - cp's OEIS frontend

A127179 Primes with prime "Look And Say" descriptions from right to left (irrespective of method A or method B).

3, 7, 71, 103, 311, 349, 757, 1297, 1327, 1811, 1993, 1999, 3119, 3709, 7027, 7297, 7573, 7603, 7639, 7873, 7883, 7963, 9001, 9043, 9311, 9613, 9677, 10739, 11159, 11177, 13121, 13553, 13721, 13751, 14369, 14831, 14897, 14939, 14951, 15329

Offset: 1

Lekraj Beedassy, Jan 07 2007

			71 and 311, for instance, belongs to the sequence because their respective descriptions 1117 (one 1, one 7) or 1171 (1 once, 7 once) and 2113 (two 1's, one 3) or 1231 (1 twice, 3 once) are all primes.

Cf. A127177, A127179, A127176.

Intersection of A127177 and A127178.

Extended by Ray Chandler, Jan 16 2007

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.

Original entry on oeis.org

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

Lekraj Beedassy, Jan 07 2007

			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.

Cf. A022481, A127177, A127179.

LookAndSayB[ n_] := FromDigits@Flatten@((Through[ {First, Length}[ # ] ] &) /@ Split@Reverse@IntegerDigits@n); Select[Prime@Range[400],PrimeQ@LookAndSayB@# &] (* Ray Chandler, Jan 16 2007 *)

Corrected by Ray Chandler, Jan 16 2007

cp's OEIS Frontend

A127179 Primes with prime "Look And Say" descriptions from right to left (irrespective of method A or method B).

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