A127175 Primes whose "Look And Say" descriptions from left to right (in the sense of method B, i.e., digit-indication followed by frequency) are also primes.

3, 7, 17, 23, 41, 89, 113, 131, 137, 163, 179, 193, 271, 281, 283, 337, 389, 431, 443, 457, 479, 587, 593, 613, 661, 673, 683, 691, 727, 739, 757, 787, 809, 829, 863, 883, 907, 983, 1009, 1051, 1087, 1123, 1153, 1163, 1181, 1213, 1229, 1249, 1279, 1297

Offset: 1

Author

Lekraj Beedassy, Jan 07 2007

Keywords

• base
• nonn

Examples

			41, 337, 809, 1123, for instance, are in the sequence because their respective descriptions 4111 (4 once, 1 once), 3271 (3 twice, 7 once), 810191 (8 once, 0 once, 9 once), 122131 (1 twice, 2 once, 3 once) are also primes.
		

Crossrefs

Cf. A007651, A056815, A127176.

Programs

Mathematica

LookAndSayB[ n_] := FromDigits@Flatten@((Through[ {First, Length}[ # ] ] &) /@ Split@IntegerDigits@n); Select[Prime@Range[215], PrimeQ@LookAndSayB@# &] (* Ray Chandler, Jan 08 2007 *)

Extensions

Corrected by Ray Chandler, Jan 08 2007