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A046312
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Numbers that are divisible by exactly 9 primes with multiplicity.
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36
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512, 768, 1152, 1280, 1728, 1792, 1920, 2592, 2688, 2816, 2880, 3200, 3328, 3888, 4032, 4224, 4320, 4352, 4480, 4800, 4864, 4992, 5832, 5888, 6048, 6272, 6336, 6480, 6528, 6720, 7040, 7200, 7296, 7424, 7488, 7936, 8000, 8320, 8748, 8832, 9072, 9408
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OFFSET
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1,1
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COMMENTS
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Also called 9-almost primes. Products of exactly 9 primes (not necessarily distinct). - Jonathan Vos Post, Dec 11 2004
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Reference
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FORMULA
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Product p_i^e_i with Sum e_i = 9.
a(n) ~ 40320n log n / (log log n)^8. - Charles R Greathouse IV, May 06 2013
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MATHEMATICA
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Select[Range[2200], Plus @@ Last /@ FactorInteger[ # ] == 9 &] - Vladimir Orlovsky, Apr 23 2008
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PROG
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(PARI) is(n)=bigomega(n)==9 \\ Charles R Greathouse IV, Mar 21 2013
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CROSSREFS
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Cf. A046311, A120050 (number of 9-almost primes <= 10^n).
Cf. A101637, A101638, A101605, A101606.
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), A046308 (r = 7), A046310 (r = 8), this sequence (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
Sequence in context: A202461 A046311 A036333 * A045033 A066648 A043423
Adjacent sequences: A046309 A046310 A046311 * A046313 A046314 A046315
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KEYWORD
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nonn
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AUTHOR
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Patrick De Geest, Jun 15 1998.
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STATUS
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approved
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