Search: id:A014613
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%I A014613
%S A014613 16,24,36,40,54,56,60,81,84,88,90,100,104,126,132,135,136,140,150,152,
%T A014613 156,184,189,196,198,204,210,220,225,228,232,234,248,250,260,276,294,
%U A014613 296,297,306,308,315,328,330,340,342,344,348,350,351,364,372,375,376
%N A014613 Numbers that are products of 4 primes (or 4-almost primes, a generalization 
               of semiprimes).
%C A014613 Also called "quadruprimes". Divisible by exactly 4 primes (counted with 
               multiplicity).
%H A014613 T. D. Noe, <a href="b014613.txt">Table of n, a(n) for n=1..10000</a>
%H A014613 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               AlmostPrime.html">Link to a section of The World of Mathematics.</
               a>
%F A014613 Product p_i^e_i with Sum e_i = 4.
%t A014613 Select[Range[200], Plus @@ Last /@ FactorInteger[ # ] == 4 &] - Vladimir 
               Orlovsky, Apr 23 2008
%Y A014613 Cf. A000040, A001358, A014614, A033987, A114106 (number of 4-almost primes 
               <= 10^n).
%Y A014613 Sequence in context: A036328 A067028 A110893 this_sequence A046370 A103248 
               A140135
%Y A014613 Adjacent sequences: A014610 A014611 A014612 this_sequence A014614 A014615 
               A014616
%K A014613 nonn
%O A014613 1,1
%A A014613 Eric Weisstein (eric(AT)weisstein.com)
%E A014613 More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 
               1998.

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