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%I #9 Oct 15 2017 13:29:28
%S 29,53,61,73,89,137,173,181,263,331,449,523,541,547,569,577,587,593,
%T 683,691,727,811,839,947,1051,1063,1153,1163,1223,1259,1289,1367,1531,
%U 1559,1627,1637,1847,1861,1933,1973,1987,2099,2153,2161,2213,2267,2287,2311
%N Primes p such that p +- 4 are semiprimes.
%C Cf. A063643 Primes p such that p +- 2 are semiprimes.
%H Harvey P. Dale, <a href="/A117328/b117328.txt">Table of n, a(n) for n = 1..1000</a>
%e 29 - 4 = 25 = 5*5 (semiprime). 29 + 4 = 33 = 3*11 (semiprime).
%t fQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; Select[ Prime@ Range[3, 345], fQ[ # - 4] && fQ[ # + 4] &] (* _Robert G. Wilson v_, May 01 2006 *)
%t Select[Prime[Range[400]],PrimeOmega[#-4]==PrimeOmega[#+4]==2&] (* _Harvey P. Dale_, Oct 15 2017 *)
%Y Cf. A063643.
%K nonn
%O 1,1
%A _Zak Seidov_, Mar 08 2006
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