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 A069279 Products of exactly 18 primes (generalization of semiprimes). 32
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Product of 18 not necessarily distinct primes. Divisible by exactly 18 prime powers (not including 1). LINKS D. W. Wilson, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Almost Prime. FORMULA Product p_i^e_i with Sum e_i = 18. MATHEMATICA Select[Range[31*10^5], PrimeOmega[#]==18&] (* Harvey P. Dale, Apr 05 2015 *) PROG (PARI) k=18; start=2^k; finish=4000000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v CROSSREFS 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 KEYWORD nonn AUTHOR Rick L. Shepherd, Mar 13 2002 STATUS approved

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Last modified October 6 12:35 EDT 2022. Contains 357264 sequences. (Running on oeis4.)