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A118722
Chen primes for which the product of the digits is also a Chen prime.
0
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
1,1
EXAMPLE
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.
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 *)
CROSSREFS
Cf. A109611.
Sequence in context: A293663 A317688 A046703 * A051026 A028865 A053435
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), May 21 2006
STATUS
approved