A210546 Emirps whose products of digits are prime.

13, 17, 31, 71, 113, 311, 1151, 1511, 111211, 112111, 1111711, 1171111, 11111117, 11113111, 11131111, 71111111, 111111131, 131111111, 1111115111, 1115111111, 11111111113, 31111111111, 111111111111111131, 131111111111111111, 1111111111111111111111111511

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..66

Prog

(Python)
from __future__ import division
from sympy import isprime
A210546_list = []
for l in range(1, 20):
    q = (10**l-1)//9
    for i in range(l):
        for p in [2, 3, 5, 7]:
            r = q+(p-1)*10**i
            s, t = str(r), str(r)[::-1]
            if s != t and isprime(r) and isprime(int(t)):
                A210546_list.append(r) # Chai Wah Wu, Aug 15 2017

Crossrefs

Cf. A006567, A046703, A210547, A210548.

Sequence in context: A272403 A159614 A158087 * A370848 A126808 A053009

Adjacent sequences: A210543 A210544 A210545 * A210547 A210548 A210549

Keyword

nonn,base

Author

Lekraj Beedassy, Mar 22 2012

Extensions

5 more terms from Alois P. Heinz, Mar 29 2012

Status

approved