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A118572
Sophie Germain primes for which the product of the digits is square.
1
11, 41, 191, 281, 419, 491, 509, 683, 809, 911, 1013, 1019, 1031, 1049, 1103, 1229, 1289, 1409, 1499, 1559, 1601, 1889, 1901, 2003, 2039, 2063, 2069, 2129, 2693, 2819, 2903, 2963, 3023, 3413, 3803, 4019, 4073, 4409, 4919, 5003, 5039, 5051, 5081, 5303
OFFSET
1,1
LINKS
EXAMPLE
1499 is in the sequence because (1) it is a Sophie Germain prime and (2) the product of its digits 1*4*9*9=324, which is a square.
MATHEMATICA
Select[Prime[Range[1000]], PrimeQ[2#+1]&&IntegerQ[Sqrt[Times@@ IntegerDigits[ #]]]&] (* Harvey P. Dale, Dec 29 2014 *)
CROSSREFS
Cf. A005384.
Sequence in context: A156733 A079304 A260270 * A333084 A201709 A092445
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), May 07 2006
STATUS
approved