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A069279
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Products of exactly 18 primes (generalization of semiprimes).
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32
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262144, 393216, 589824, 655360, 884736, 917504, 983040, 1327104, 1376256, 1441792, 1474560, 1638400, 1703936, 1990656, 2064384, 2162688, 2211840, 2228224, 2293760, 2457600, 2490368, 2555904, 2985984, 3014656, 3096576
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OFFSET
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1,1
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COMMENTS
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Product of 18 not necessarily distinct primes.
Divisible by exactly 18 prime powers (not including 1).
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LINKS
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D. W. Wilson, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Almost Prime.
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FORMULA
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Product p_i^e_i with Sum e_i = 18.
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MATHEMATICA
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Select[Range[31*10^5], PrimeOmega[#]==18&] (* Harvey P. Dale, Apr 05 2015 *)
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PROG
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(PARI) k=18; start=2^k; finish=4000000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v
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CROSSREFS
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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), 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), this sequence (r = 18), A069280 (r = 19), A069281 (r = 20). - Jason Kimberley, Oct 02 2011
Sequence in context: A186873 A018867 A057445 * A068961 A224806 A224803
Adjacent sequences: A069276 A069277 A069278 * A069280 A069281 A069282
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KEYWORD
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nonn
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AUTHOR
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Rick L. Shepherd, Mar 13 2002
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STATUS
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approved
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