A046705 Palindromic primes whose product of digits is a prime.

2, 3, 5, 7, 131, 151, 11311, 1117111, 111111151111111, 111111111111111111131111111111111111111, 1111111111111111111111111111111117111111111111111111111111111111111, 1111111111111111111111111111111111111111111115111111111111111111111111111111111111111111111

Offset: 1

Author

Felice Russo

Keywords

• base
• nonn

Comments

Except for the first 4 terms, a subsequence of A088281. - Chai Wah Wu, Dec 17 2015

Subsequence of A028842, of A046703, and also of A117058. - Michel Marcus, Dec 18 2015

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..15

Crossrefs

Cf. A028842, A046703, A088281, A117058.

Programs

Mathematica

t = Prime[Range[4]]; Union[Select[Flatten[Table[NestList[FromDigits[Flatten[{1, IntegerDigits[#], 1}]] &, n, 45], {n, t}]], PrimeQ]] (* Jayanta Basu, Jun 27 2013 *)

Python

from _future_ import division
from sympy import isprime
A046705_list = [n for n in ((10**(2*l+1)-1)//9+d*10**l for l in range(100) for d in [1,2,4,6]) if isprime(n)] # Chai Wah Wu, Dec 17 2015