A028842 Numbers whose product of digits is prime.

2, 3, 5, 7, 12, 13, 15, 17, 21, 31, 51, 71, 112, 113, 115, 117, 121, 131, 151, 171, 211, 311, 511, 711, 1112, 1113, 1115, 1117, 1121, 1131, 1151, 1171, 1211, 1311, 1511, 1711, 2111, 3111, 5111, 7111, 11112, 11113, 11115, 11117, 11121, 11131, 11151

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..130
• Index entries for 10-automatic sequences

Crossrefs

Cf. A007954, A028843, A028834, A046703 (subsequence of primes).

Programs

Mathematica

Select[Range[11160], PrimeQ[Times@@IntegerDigits[#]] &] (* Jayanta Basu, Jun 02 2013 *)

PARI

isok(n) = isprime(vecprod(digits(n))); \\ Michel Marcus, Apr 17 2020

PARI

is(n)=my(d=digits(n),p); for(i=1,#d,if(d[i]==1,next); if(isprime(d[i]) && !p, p=1, return(0))); p \\ Charles R Greathouse IV, Apr 18 2020

Sage

[x for x in range(10^5) if (prod(Integer(x).digits(base=10))) in Primes()] # Bruno Berselli, May 05 2014

Scala

(1 to 10000).filter(n => List(2, 3, 5, 7).contains(n.toString.toCharArray.map( - 48).scanRight(1)( * ).head)) // _Alonso del Arte, Apr 14 2020

Extensions

More terms from Erich Friedman.

Name edited by Jianing Song, Jul 07 2025