|
%I #26 Jul 02 2021 01:53:31
%S 15,21,33,39,55,69,85,91,111,115,129,133,141,159,183,201,213,235,253,
%T 259,265,295,309,319,339,355,381,391,403,411,445,451,469,481,489,493,
%U 501,505,511,543,559,565,573,579,589,633,649,655,679,685
%N Numbers k such that k is a product of two different primes and k-2 is prime.
%H Zak Seidov and Michael De Vlieger, <a href="/A043326/b043326.txt">Table of n, a(n) for n = 1..21728</a> (first 10000 terms from Zak Seidov)
%t Select[Range[700],PrimeOmega[#]==PrimeNu[#]==2&&PrimeQ[#-2]&] (* _Harvey P. Dale_, Feb 01 2014 *)
%t Select[Prime[Range[200]]+2,PrimeOmega[#]==PrimeNu[#]==2&] (* _Harvey P. Dale_, Oct 13 2018 *)
%o (PARI) is(n)=isprime(n-2) && bigomega(n)==2 && !issquare(n) \\ _Charles R Greathouse IV_, Jul 20 2014
%Y Cf. A006512, A062721.
%Y Subsequence of A006881.
%K nonn
%O 1,1
%A _Olivier Gérard_, Jul 19 2001
|
