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%I #14 May 11 2023 09:21:17
%S 27,35,51,57,65,77,87,95,125,135,147,155,161,171,177,189,209,221,237,
%T 249,255,261,267,275,291,305,329,335,345,357,365,371,377,387,395,407,
%U 417,429,437,447,455,477,485,497,507,519,539,545,555,561,567,575,585
%N Odd nonprimes such that the prior odd number is not a prime but the next odd number is a prime.
%H Harvey P. Dale, <a href="/A134101/b134101.txt">Table of n, a(n) for n = 1..1000</a>
%e a(1)=27 because this odd nonprime is followed by the prime 29 but preceded by the odd nonprime 25.
%t Select[Range[5,1000,2],!PrimeQ[#]&&!PrimeQ[#-2]&&PrimeQ[#+2]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 03 2012 *)
%t Transpose[Select[Partition[Range[1,601,2],3,1],Boole[PrimeQ[#]]=={0,0,1}&]] [[2]] (* or *) 2#+1&/@Flatten[Position[Partition[Boole[PrimeQ[ Range[ 1,601,2]]],3,1],_?(#=={0,0,1}&)]] (* _Harvey P. Dale_, Jan 04 2015 *)
%o (UBASIC) 10 'primes using counters 20 N=3:print "2 ";:print "3 ";:C=2 30 A=3:S=sqrt(N) 40 B=N\A 50 if B*A=N then 55 55 Q=N-2:R=N+2: if Q<>prmdiv(Q) and N<>prmdiv(N) and R=prmdiv(R) then print Q;N;R;"-";:stop:else N=N+2:goto 30 60 A=A+2 70 if A<=sqrt(N) then 40:stop 81 C=C+1 100 N=N+2:goto 30
%Y Cf. A134100 A134099 A083370 A124582 A007510.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Oct 08 2007
%E Definition clarified by _Harvey P. Dale_, Jan 04 2015
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