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

1,1

Links

Table of n, a(n) for n=1..50.

Example

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.

Mathematica

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

Crossrefs

Cf. A007651, A056815, A127176.

Sequence in context: A152451 A097958 A118940 * A339943 A127355 A079470

Adjacent sequences: A127172 A127173 A127174 * A127176 A127177 A127178

Keyword

base,nonn

Author

Lekraj Beedassy, Jan 07 2007

Extensions

Corrected by Ray Chandler, Jan 08 2007

Status

approved