|
|
A141263
|
|
Lesser of a prime/emirp pair.
|
|
2
|
|
|
2, 3, 5, 7, 11, 13, 17, 37, 79, 101, 107, 113, 131, 149, 151, 157, 167, 179, 181, 191, 199, 313, 337, 347, 353, 359, 373, 383, 389, 709, 727, 739, 757, 769, 787, 797, 919, 929, 1009, 1021, 1031, 1033, 1061, 1069, 1091, 1097, 1103, 1109, 1151, 1153, 1181
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
From the set of numbers that are both prime and emirp choose the smaller one of each pair (whenever more than one decimal digit is involved).
A002385 is subset of this sequence.
|
|
LINKS
|
|
|
EXAMPLE
|
31 does not appear since we have already seen 13.
|
|
MATHEMATICA
|
pp[n_] := Module[{nr=FromDigits[Reverse[IntegerDigits[n]]]}, If[PrimeQ[nr], Sort[{n, nr}]]]; Transpose[Rest[Union[pp/@Prime[Range[200]]]]][[1]] (* Harvey P. Dale, Dec 18 2010 *)
|
|
PROG
|
(Python)
from gmpy2 import next_prime, is_prime
for _ in range(1, 10**4):
....p = next_prime(p)
....ps = int(str(p)[::-1])
....if p <= ps and is_prime(ps):
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|