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Search: id:A046308
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| A046308 |
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Numbers that are divisible by exactly 7 primes (counted with multiplicity). |
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25
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| 128, 192, 288, 320, 432, 448, 480, 648, 672, 704, 720, 800, 832, 972, 1008, 1056, 1080, 1088, 1120, 1200, 1216, 1248, 1458, 1472, 1512, 1568, 1584, 1620, 1632, 1680, 1760, 1800, 1824, 1856, 1872, 1984, 2000, 2080, 2187, 2208, 2268, 2352, 2368, 2376
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also called 7-almost primes. Products of exactly 7 primes (not necessarily distinct). - Jonathan Vos Post (jvospost2(AT)yahoo.com), 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 = 7.
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MATHEMATICA
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Select[Range[900], Plus @@ Last /@ FactorInteger[ # ] == 7 &] - Vladimir Orlovsky, Apr 23 2008
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CROSSREFS
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Cf. A046306, A046307, A046310, A120048 (number of 7-almost primes <= 10^n).
Cf. A014612, A001358, A101605, A101606.
Sequence in context: A114418 A046307 A036331 this_sequence A110290 A045028 A045053
Adjacent sequences: A046305 A046306 A046307 this_sequence A046309 A046310 A046311
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KEYWORD
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nonn
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1998.
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