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 A069276 15-almost primes (generalization of semiprimes). 27
 32768, 49152, 73728, 81920, 110592, 114688, 122880, 165888, 172032, 180224, 184320, 204800, 212992, 248832, 258048, 270336, 276480, 278528, 286720, 307200, 311296, 319488, 373248, 376832, 387072, 401408, 405504, 414720, 417792, 430080 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Product of 15 not necessarily distinct primes. Divisible by exactly 15 prime powers (not including 1). Any 15-almost prime can be represented in several ways as a product of three 5-almost primes A014614, and in several ways as a product of five 3-almost primes A014612. - Jonathan Vos Post, Dec 11 2004 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 = 15. MATHEMATICA Select[Range[90000], Plus @@ Last /@ FactorInteger[ # ] == 15 &] (* Vladimir Joseph Stephan Orlovsky, Apr 23 2008 *) PROG (PARI) k=15; start=2^k; finish=500000; 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), this sequence (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: A222528 A232393 A217589 * A195235 A223335 A194934 Adjacent sequences:  A069273 A069274 A069275 * A069277 A069278 A069279 KEYWORD nonn AUTHOR Rick L. Shepherd, Mar 13 2002 STATUS approved

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Last modified December 14 21:22 EST 2018. Contains 318138 sequences. (Running on oeis4.)