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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

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

Adjacent sequences:  A118719 A118720 A118721 * A118723 A118724 A118725

KEYWORD

base,nonn

AUTHOR

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

STATUS

approved

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Last modified October 19 03:34 EDT 2019. Contains 328211 sequences. (Running on oeis4.)