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A157356 Products (semiprimes) of two distinct double-safe primes. 1
253, 517, 1081, 1837, 3841, 3949, 7849, 7909, 8257, 15829, 16537, 16873, 22429, 31669, 33097, 33793, 44869, 45397, 46897, 54109, 59953, 62029, 63877, 65197, 66217, 66517, 67633, 79717, 83149, 83677, 84997, 93817, 94921, 95833, 108229 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
253=11*23; 11 and 23 are double safe prime numbers; (11-1)/2=5; (5-1)/2=2(prime); (23-1)/2=11; (11-1)/2=5(prime), ...
LINKS
MATHEMATICA
lst={}; Do[If[Plus@@Last/@FactorInteger[n]==2, a=Length[First/@FactorInteger[n]]; If[a==2, b=First/@FactorInteger[n]; c=b[[1]]; d=b[[2]]; If[PrimeQ[cx=(c-1)/2]&&PrimeQ[(cx-1)/2]&&PrimeQ[dx=(d-1)/2]&&PrimeQ[(dx-1)/2], AppendTo[lst, n]]]], {n, 9!}]; lst
CROSSREFS
Sequence in context: A244168 A002289 A158078 * A203085 A245790 A070193
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 1 14:53 EST 2024. Contains 370433 sequences. (Running on oeis4.)