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%I #16 Feb 04 2023 05:30:04
%S 6,12,14,18,20,24,30,38,42,44,48,54,60,62,68,72,74,80,84,90,98,102,
%T 104,108,110,114,132,138,140,150,152,158,164,168,174,180,182,192,194,
%U 198,200,212,224,228,230,234,240,242,252,258,264,270,272,278,282,284,294
%N Composites one larger than a prime and with exactly two or three distinct prime factors.
%H Robert Israel, <a href="/A136155/b136155.txt">Table of n, a(n) for n = 1..10000</a>
%F Union of A136151 and A136152. Subset of A008864. - _R. J. Mathar_, Apr 24 2008
%F A136151 UNION A136152. - _R. J. Mathar_, May 03 2008
%e a(1)=6, which is one larger than the prime 5 and has 2 distinct prime factors (namely 2 and 3).
%e 60 is in the sequence because 59 is prime and 60 = 2^2*3*5 has three distinct prime factors.
%p A001221 := proc(n) nops(numtheory[factorset](n)) ; end: isA136155 := proc(n) if isprime(n-1) then RETURN( A001221(n)=2 or A001221(n)= 3) ; else RETURN(false) ; fi ; end: for n from 1 to 300 do if isA136155(n) then printf("%d,",n) ; fi ; od: # _R. J. Mathar_, May 03 2008
%t okQ[n_] := PrimeQ[n-1] && (PrimeNu[n]==2 || PrimeNu[n]==3);
%t Select[Range[6, 300, 2], okQ] (* _Jean-François Alcover_, Feb 04 2023 *)
%Y Cf. A136151, A136152, A136153, A136154.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Dec 16 2007
%E Edited by _R. J. Mathar_ and _Jens Kruse Andersen_, Apr 24 2008