|
Search: id:A157342
|
|
|
| A157342 |
|
Semiprimes : products of two not-Sophie Germain primes. |
|
+0
12
|
|
| 49, 91, 119, 133, 169, 217, 221, 247, 259, 289, 301, 323, 329, 361, 403, 413, 427, 469, 481, 497, 511, 527, 553, 559, 589, 611, 629, 679, 703, 707, 721, 731, 749, 763, 767, 793, 799, 817, 871, 889, 893, 923, 949, 959, 961, 973, 1003, 1027, 1037, 1043, 1057
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
49=7*7;2*7+1=15(not Prime), 91=7*13;2*7+1=15(not Prime);2*13+1=27(not Prime), ...
|
|
MATHEMATICA
|
lst={}; Do[If[Plus@@Last/@FactorInteger[n]==2, a=First/@FactorInteger[n]; b=a[[1]]; k=0; If[Length[a]==2, c=a[[2]]; If[PrimeQ[2*c+1], k=1]]; If[ !PrimeQ[2*b+1]&&k==0, AppendTo[lst, n]]], {n, 7!}]; lst
|
|
CROSSREFS
|
Cf. A001358, A005384, A111206
Sequence in context: A093894 A158725 A090825 this_sequence A118886 A108164 A020158
Adjacent sequences: A157339 A157340 A157341 this_sequence A157343 A157344 A157345
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladimir Orlovsky (4vladimir(AT)gmail.com), Feb 27 2009
|
|
|
Search completed in 0.002 seconds
|
