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A285805 Prime numbers p such that 6*p-1 and 6*p+1 are composite numbers.

%I A285805 #27 Jun 10 2022 12:22:07
%S A285805 31,41,71,79,89,97,139,149,167,179,191,193,211,223,251,281,307,337,
%T A285805 349,353,401,409,419,421,431,433,479,487,491,499,509,521,541,547,563,
%U A285805 571,587,619,631,643,659,673,677,691,701,719,739,757,769,809
%N A285805 Prime numbers p such that 6*p-1 and 6*p+1 are composite numbers.
%H A285805 Robert Israel, <a href="/A285805/b285805.txt">Table of n, a(n) for n = 1..10000</a>
%p A285805 filter:= n -> isprime(n) and not isprime(6*n-1) and not isprime(6*n+1):
%p A285805 select(filter, [seq(i,i=3..1000,2)]); # _Robert Israel_, Jan 05 2020
%t A285805 Select[Prime@Range@150, ! PrimeQ[6 # - 1] && ! PrimeQ[6 # + 1] &] (* _Robert G. Wilson v_, Apr 27 2017 *)
%t A285805 Select[Prime[Range[150]],NoneTrue[6#+{1,-1},PrimeQ]&] (* _Harvey P. Dale_, Jun 10 2022 *)
%o A285805 (PARI) {forprime(n=3, 1000, if(!isprime(6*n-1)&&!isprime(6*n+1), print1(n", ")))}
%Y A285805 Cf. A060212, A099047.
%K A285805 nonn
%O A285805 1,1
%A A285805 _Dimitris Valianatos_, Apr 26 2017