A141263 Lesser of a prime/emirp pair.

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

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

Chai Wah Wu, Table of n, a(n) for n = 1..1000

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
A141263_list, p = [], 1
for _ in range(1, 10**4):
    p = next_prime(p)
    ps = int(str(p)[::-1])
    if p <= ps and is_prime(ps):
        A141263_list.append(int(p)) # Chai Wah Wu, Jun 11 2015

Crossrefs

Cf. A002385, A007500.

Sequence in context: A118725 A117835 A120639 * A016114 A263499 A258706

Adjacent sequences: A141260 A141261 A141262 * A141264 A141265 A141266

Keyword

nonn,base

Author

Artur Jasinski, Jun 20 2008

Status

approved