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%I #10 Oct 05 2015 16:02:39
%S 5,7,11,13,19,29,59,67,73,79,89,103,127,149,163,167,181,191,227,241,
%T 251,257,263,269,271,277,283,311,347,353,359,373,383,389,397,401,409,
%U 433,439,449,457,467,479,487,503,523,541,557,571,599,601,613,643,647,659,677,691,709,719,733,739,751,757,769,811,827,839,853
%N Primes p that exactly one of 2p-1, 2p+1 is semiprime.
%H Harvey P. Dale, <a href="/A176579/b176579.txt">Table of n, a(n) for n = 1..1000</a>
%e a(1)=5 because 2*5-1=9=semiprime and 2*5+1=11=non-semiprime.
%p Contribution from _R. J. Mathar_, Dec 12 2010: (Start)
%p isA001358 := proc(n) is(numtheory[bigomega](n) = 2) ; end proc:
%p for n from 1 to 120 do p := ithprime(n) ; if isA001358(2*p-1) <> isA001358(2*p+1) then printf("%d,",p); end if; end do: (End)
%t Select[Prime[Range[200]],Count[PrimeOmega[2#+{1,-1}],2]==1&] (* _Harvey P. Dale_, Oct 05 2015 *)
%Y Cf. A001358.
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Apr 20 2010
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