|
Search: id:A118724
|
|
|
| A118724 |
|
Chen primes for which the multiplicative digital root is also a Chen prime. |
|
+0
1
|
|
| 2, 3, 5, 7, 13, 17, 31, 37, 53, 71, 113, 131, 137, 157, 211, 311, 317, 359, 389, 431, 557, 571, 751, 827, 839, 953, 983, 1117, 1151, 1297, 1367, 1511, 1553, 1621, 1637, 1759, 2111, 2179, 2213, 2269, 2339, 2393, 2699, 2719, 2969, 2971, 3167, 3221, 3329, 3511
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
157 is in the sequence because (1) it is a Chen prime and (2) the multiplicative digital root 5 is also a Chen prime.
|
|
MATHEMATICA
|
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 *)
|
|
CROSSREFS
|
Cf. A109611.
Sequence in context: A087520 A117159 A134873 this_sequence A046732 A046703 A118722
Adjacent sequences: A118721 A118722 A118723 this_sequence A118725 A118726 A118727
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), May 21 2006
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(at)rgwv.com), May 22 2006
|
|
|
Search completed in 0.002 seconds
|
