1,1

Table of n, a(n) for n=1..50.

157 is in the sequence because (1) it is a Chen prime and (2) the multiplicative digital root 5 is also a Chen prime.

mdr[n_] := NestWhile[Times @@ IntegerDigits@# &, n, # > 9 &]; chenQ[n_] := PrimeQ[n] && Plus @@ Last /@ FactorInteger[n + 2] < 3; Select[ Prime@ Range@500, chenQ@ mdr@# && chenQ@# &] (* Robert G. Wilson v *)

Cf. A109611.

Sequence in context: A117159 A134873 A172979 * A046732 A293663 A046703

Adjacent sequences: A118721 A118722 A118723 * A118725 A118726 A118727

base,nonn

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

More terms from Robert G. Wilson v, May 22 2006

approved