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%I #9 Feb 02 2017 00:09:00
%S 24,54,90,140,210,315,462,550,650,858,1122,1190,1330,1482,1794,2254,
%T 2499,2805,3135,3306,3596,4030,4485,5106,5698,6314,6970,7310,7482,
%U 7917,8463,8742,8930,10070,11766,12765,13570,14042,14399,14762,15006,15867
%N 4-almost primes equal to the product of two successive semiprimes.
%H Harvey P. Dale, <a href="/A108215/b108215.txt">Table of n, a(n) for n = 1..1000</a>
%e a(1) = 4*6 = 24 and a(2) = 6*9 = 54 because 4, 6 and 9 are the first three successive semiprimes.
%t Select[Times@@@Partition[Select[Range[200],PrimeOmega[#]==2&],2,1], PrimeOmega[#]==4&] (* _Harvey P. Dale_, Nov 17 2011 *)
%o (PARI) sp=4; for(sq=6,300, if(bigomega(sq)==2, print1(sp*sq,","); sp=sq)) \\ _Rick L. Shepherd_
%o (PARI) list(lim)=my(v=List(),s=sqrtint(lim\1),u=v); forprime(p=2,s\2, forprime(q=2,min(p,s\p), listput(v,p*q))); v=Set(v); for(i=2,#v, listput(u, v[i-1]*v[i])); for(k=s+1,lim\v[#v], if(bigomega(k)==2, listput(u, v[#v]*k); break)); Set(u) \\ _Charles R Greathouse IV_, Feb 02 2017
%K easy,nonn
%O 1,1
%A _Giovanni Teofilatto_, Jun 16 2005
%E More terms from _Rick L. Shepherd_, Jun 16 2005
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