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A242260 Primes p such that p^2-2 is semiprime. 2

%I #10 Nov 17 2019 22:37:52

%S 11,17,23,31,41,53,67,73,79,83,97,109,113,149,151,163,167,197,199,229,

%T 241,251,269,281,307,331,349,379,383,389,401,433,439,457,461,463,503,

%U 547,563,593,599,601,613,617,631,643,659,661,673,691,701,709,739,769

%N Primes p such that p^2-2 is semiprime.

%H Robert Israel, <a href="/A242260/b242260.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= t -> isprime(t) and numtheory:-bigomega(t^2-2)=2:

%p select(filter, [seq(i,i=3..10000,2)]); # _Robert Israel_, Nov 17 2019

%t Select[Table[Prime[k], {k, 1000}], PrimeOmega[#^2 - 2] == 2 &] (* M7*)

%o (PARI) s=[]; forprime(p=2, 1000, if(bigomega(p^2-2)==2, s=concat(s, p))); s \\ _Colin Barker_, May 10 2014

%Y Subsequence of A219602. Cf. A001358.

%K nonn

%O 1,1

%A _Zak Seidov_, May 09 2014

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Last modified April 25 01:06 EDT 2024. Contains 371964 sequences. (Running on oeis4.)