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A157353 Products (semiprimes) of two distinct not-safe primes. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

6=2*3; 2 and 3 are not safe prime numbers, 26=2*3; 2 and 13 are not safe prime numbers,...

LINKS

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

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

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Last modified November 17 13:33 EST 2019. Contains 329230 sequences. (Running on oeis4.)