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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 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 April 19 05:22 EDT 2014. Contains 240738 sequences.