OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
EXAMPLE
30 = 2*3*5; 2,3 and 5 are distinct Sophie Germain primes.
66 = 2*3*11; 2,3 and 11 are distinct Sophie Germain primes.
MATHEMATICA
lst={}; Do[If[Plus@@Last/@FactorInteger[n]==3, a=Length[First/@FactorInteger[n]]; If[a==3, b=First/@FactorInteger[n]; c=b[[1]]; d=b[[2]]; e=b[[3]]; If[PrimeQ[2*c+1]&&PrimeQ[2*d+1]&&PrimeQ[2*e+1], AppendTo[lst, n]]]], {n, 7!}]; lst
With[{sgps=Select[Prime[Range[100]], PrimeQ[2#+1]&]}, Take[Union[ Times@@@ Subsets[sgps, {3}]], 60]] (* Harvey P. Dale, Aug 10 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Feb 27 2009
STATUS
approved