A157346 Products of 3 distinct Sophie Germain primes.

30, 66, 110, 138, 165, 174, 230, 246, 290, 318, 345, 410, 435, 498, 506, 530, 534, 615, 638, 678, 759, 786, 795, 830, 890, 902, 957, 1038, 1074, 1130, 1146, 1166, 1245, 1265, 1310, 1334, 1335, 1353, 1398, 1434, 1506, 1595, 1686, 1695, 1730, 1749, 1758, 1790

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

Cf. A001358, A005384, A111206, A157342, A006881, A157344, A157345, A007304.

Sequence in context: A044513 A209876 A290145 * A219543 A309393 A154055

Adjacent sequences: A157343 A157344 A157345 * A157347 A157348 A157349

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

Status

approved