Search: id:A033993
Results 1-1 of 1 results found.

%I A033993
%S A033993 210,330,390,420,462,510,546,570,630,660,690,714,770,780,798,840,858,
%T A033993 870,910,924,930,966,990,1020,1050,1092,1110,1122,1140,1155,1170,1190,
%U A033993 1218,1230,1254,1260,1290,1302,1320,1326,1330,1365,1380,1386,1410,1428
%N A033993 Numbers that are divisible by exactly four different primes.
%C A033993 For a(n) < 30030 = 2 * 3 * 5 * 7 * 11 * 13 this is identical to "numbers 
               with a semiprime number of distinct prime factors." - Jonathan Vos 
               Post (jvospost3(AT)gmail.com), Sep 21 2005
%H A033993 T. D. Noe, <a href="b033993.txt">Table of n, a(n) for n=1..1000</a>
%F A033993 a(n) has exactly 4 distinct prime factors. omega(a(n)) = A001221(a(n)) 
               = 4. - Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 21 2005
%e A033993 The 4th primorial is the first: A002110[ 4 ]=210.
%Y A033993 A000977, A007774, A000961, A002110, A033992, A051270.
%Y A033993 Cf. A001221.
%Y A033993 Sequence in context: A125011 A119427 A074159 this_sequence A046386 A046402 
               A147571
%Y A033993 Adjacent sequences: A033990 A033991 A033992 this_sequence A033994 A033995 
               A033996
%K A033993 nonn
%O A033993 1,1
%A A033993 Labos E. (labos(AT)ana.sote.hu)

Search completed in 0.002 seconds