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 A046386 Products of four distinct primes. 30
 210, 330, 390, 462, 510, 546, 570, 690, 714, 770, 798, 858, 870, 910, 930, 966, 1110, 1122, 1155, 1190, 1218, 1230, 1254, 1290, 1302, 1326, 1330, 1365, 1410, 1430, 1482, 1518, 1554, 1590, 1610, 1722, 1770, 1785, 1794, 1806, 1830, 1870, 1914, 1938, 1974 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A squarefree subsequence of A033993. Numbers like 420 = 2^2*3*5*7 with at least one prime exponent greater than 1 in the prime signature are excluded here. - R. J. Mathar, Apr 03 2011 Numbers such that omega(n)=bigomega(n)=4. - Michel Marcus, Dec 15 2015 LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 EXAMPLE 210 = 2*3*5*7. 330 = 2*3*5*11. 390 = 2*3*5*13. 462 = 2*3*7*11. MATHEMATICA fQ[n_] := Last /@ FactorInteger[n] == {1, 1, 1, 1}; Select[ Range[2000], fQ[ # ] &] (* Robert G. Wilson v, Aug 04 2005 *) PROG (PARI) is(n)=factor(n)[, 2]==[1, 1, 1, 1]~ \\ Charles R Greathouse IV, Sep 17 2015 CROSSREFS Cf. A046387, A067885 (product of 5 and 6 distinct primes, resp.) Cf. A006881, A007304, A014613, A046402. Sequence in context: A127424 A074159 A033993 * A229272 A046402 A258359 Adjacent sequences:  A046383 A046384 A046385 * A046387 A046388 A046389 KEYWORD nonn,easy AUTHOR Patrick De Geest, Jun 15 1998 STATUS approved

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Last modified December 9 19:14 EST 2018. Contains 318023 sequences. (Running on oeis4.)