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%I #36 Jan 30 2019 09:40:35
%S 128,192,288,320,432,448,480,648,672,704,720,800,832,972,1008,1056,
%T 1080,1088,1120,1200,1216,1248,1458,1472,1512,1568,1584,1620,1632,
%U 1680,1760,1800,1824,1856,1872,1984,2000,2080,2187,2208,2268,2352,2368,2376
%N Numbers that are divisible by exactly 7 primes counting multiplicity.
%C Also called 7-almost primes. Products of exactly 7 primes (not necessarily distinct). - _Jonathan Vos Post_, Dec 11 2004
%C Also, positions of 7 in A001222. - _Zak Seidov_, Oct 14 2012
%H T. D. Noe, <a href="/A046308/b046308.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/AlmostPrime.html">Reference</a>
%F Product p_i^e_i with sum e_i = 7.
%F a(n) ~ 720n log n / (log log n)^6. - _Charles R Greathouse IV_, May 06 2013
%F a(n) = A078840(7,n). - _R. J. Mathar_, Jan 30 2019
%t Select[Range[900], Plus @@ Last /@ FactorInteger[ # ] == 7 &] (* _Vladimir Joseph Stephan Orlovsky_, Apr 23 2008 *)
%o (PARI) is(n)=bigomega(n)==7 \\ _Charles R Greathouse IV_, Mar 21 2013
%Y Cf. A120048 (number of 7-almost primes <= 10^n).
%Y Cf. A101605, A101606, A001222.
%Y Sequences listing r-almost primes, that is, the n such that A001222(n) = r: A000040 (r = 1), A001358 (r = 2), A014612 (r = 3), A014613 (r = 4), A014614 (r = 5), A046306 (r = 6), this sequence (r = 7), A046310 (r = 8), A046312 (r = 9), A046314 (r = 10), A069272 (r = 11), A069273 (r = 12), A069274 (r = 13), A069275 (r = 14), A069276 (r = 15), A069277 (r = 16), A069278 (r = 17), A069279 (r = 18), A069280 (r = 19), A069281 (r = 20). - _Jason Kimberley_, Oct 02 2011
%K nonn
%O 1,1
%A _Patrick De Geest_, Jun 15 1998
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