A118722 Chen primes for which the product of the digits is also a Chen prime.

2, 3, 5, 7, 13, 17, 31, 71, 113, 131, 211, 311, 1117, 1151, 1511, 2111, 11117, 11171, 131111, 311111, 511111, 1111151, 1111211, 1111711, 1117111, 11111117, 11111171, 71111111

Offset: 1

Author

Luc Stevens (lms022(AT)yahoo.com), May 21 2006

Keywords

• base
• nonn

Examples

			31 is in the sequence because (1) it is a Chen prime and (2) the product of its digits 3*1=3 is also a Chen prime.
		

Crossrefs

Cf. A109611.

Programs

Mathematica

chenQ[n_]:=Module[{pidn=Times@@IntegerDigits[n]},PrimeQ[pidn]&&PrimeOmega[ pidn+2]<3]; With[{chen=Select[Prime[Range[4200000]],PrimeOmega[#+2]<3&]},Select[chen,chenQ]] (* Harvey P. Dale, Apr 22 2012 *)