login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A157355 Products of 3 distinct not safe primes. 2
78, 102, 114, 174, 186, 222, 246, 258, 318, 366, 402, 426, 438, 442, 474, 494, 534, 582, 606, 618, 646, 654, 663, 678, 741, 754, 762, 786, 806, 822, 834, 894, 906, 942, 962, 969, 978, 986, 1038, 1054, 1066, 1086, 1102, 1118, 1131, 1146, 1158, 1178, 1182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

78=2*3*13; 2,3 and 13 are not safe prime numbers,...

LINKS

Table of n, a(n) for n=1..49.

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

CROSSREFS

Cf. A001358, A005384, A005385, A006881, A007304, A111206, A157342, A157344, A157345, A157346, A157347, A157352, A157353, A157354

Sequence in context: A295699 A025387 A025378 * A224666 A161596 A275218

Adjacent sequences:  A157352 A157353 A157354 * A157356 A157357 A157358

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 11 05:30 EDT 2021. Contains 342886 sequences. (Running on oeis4.)