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A069276
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15-almost primes (generalization of semiprimes).
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27
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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; internal format)
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OFFSET
| 1,1
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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 (jvospost3(AT)gmail.com), Dec 11 2004
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LINKS
| D. W. Wilson, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
| Product p_i^e_i with Sum e_i = 15.
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MATHEMATICA
| Select[Range[90000], Plus @@ Last /@ FactorInteger[ # ] == 15 &] - Vladimir Orlovsky, Apr 23 2008
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PROG
| (PARI) k=15; start=2^k; finish=500000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v
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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: A161157 A069390 A069416 * A195235 A194934 A016997
Adjacent sequences: A069273 A069274 A069275 * A069277 A069278 A069279
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KEYWORD
| nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), Mar 13 2002
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