A157353 Products (semiprimes) of two distinct primes that are not safe primes.

6, 26, 34, 38, 39, 51, 57, 58, 62, 74, 82, 86, 87, 93, 106, 111, 122, 123, 129, 134, 142, 146, 158, 159, 178, 183, 194, 201, 202, 206, 213, 218, 219, 221, 226, 237, 247, 254, 262, 267, 274, 278, 291, 298, 302, 303, 309, 314, 323, 326, 327, 339, 346, 362, 377

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Example

6=2*3; 2 and 3 are not safe primes.
26=2*13; 2 and 13 are not safe primes.

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[(c-1)/2]&&!PrimeQ[(d-1)/2], AppendTo[lst, n]]]], {n, 7!}]; lst

Crossrefs

Cf. A001358, A005384, A005385, A006881, A007304, A111206, A157342, A157344, A157345, A157346, A157347, A157352.

Sequence in context: A043006 A076284 A177220 * A271311 A075454 A075456

Adjacent sequences: A157350 A157351 A157352 * A157354 A157355 A157356

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

Status

approved