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Search: id:A069276
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| A069276 |
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15-almost primes (generalization of semiprimes). |
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+0
9
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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; listen)
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OFFSET
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1,1
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COMMENT
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Divisible by exactly 15 primes (counted with multiplicity).
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
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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
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Product p_i^e_i with Sum e_i = 15.
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MATHEMATICA
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Select[Range[90000], Plus @@ Last /@ FactorInteger[ # ] == 15 &] - Vladimir Orlovsky, Apr 23 2008
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PROGRAM
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(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
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Cf. A001358 (semiprimes), A069275 (14-almost primes), A069277 (16-almost primes) - A069281 (20-almost primes).
Cf. A014612, A014614, A001358, A101637, A101638, A101605, A101606.
Sequence in context: A022531 A069390 A069416 this_sequence A016997 A017069 A017261
Adjacent sequences: A069273 A069274 A069275 this_sequence A069277 A069278 A069279
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KEYWORD
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nonn
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AUTHOR
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Rick L. Shepherd (rshepherd2(AT)hotmail.com), Mar 13 2002
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