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A043326 Numbers n such that n is a product of two different primes and n-2 is prime. 4
15, 21, 33, 39, 55, 69, 85, 91, 111, 115, 129, 133, 141, 159, 183, 201, 213, 235, 253, 259, 265, 295, 309, 319, 339, 355, 381, 391, 403, 411, 445, 451, 469, 481, 489, 493, 501, 505, 511, 543, 559, 565, 573, 579, 589, 633, 649, 655, 679, 685 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Zak Seidov and Michael De Vlieger, Table of n, a(n) for n = 1..21728 (first 10000 terms from Zak Seidov)

MATHEMATICA

Select[Range[700], PrimeOmega[#]==PrimeNu[#]==2&&PrimeQ[#-2]&] (* Harvey P. Dale, Feb 01 2014 *)

Select[Prime[Range[200]]+2, PrimeOmega[#]==PrimeNu[#]==2&] (* Harvey P. Dale, Oct 13 2018 *)

PROG

(PARI) is(n)=isprime(n-2) && bigomega(n)==2 && !issquare(n) \\ Charles R Greathouse IV, Jul 20 2014

CROSSREFS

Cf. A006512, A062721.

Sequence in context: A177516 A127329 A099610 * A179996 A079814 A168354

Adjacent sequences:  A043323 A043324 A043325 * A043327 A043328 A043329

KEYWORD

nonn

AUTHOR

Olivier Gérard, Jul 19 2001

STATUS

approved

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Last modified April 24 10:24 EDT 2019. Contains 322422 sequences. (Running on oeis4.)