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A069272
11-almost primes (generalization of semiprimes).
34
2048, 3072, 4608, 5120, 6912, 7168, 7680, 10368, 10752, 11264, 11520, 12800, 13312, 15552, 16128, 16896, 17280, 17408, 17920, 19200, 19456, 19968, 23328, 23552, 24192, 25088, 25344, 25920, 26112, 26880, 28160, 28800, 29184, 29696
OFFSET
1,1
COMMENTS
Product of 11 not necessarily distinct primes.
Divisible by exactly 11 prime powers (not including 1).
LINKS
Eric Weisstein's World of Mathematics, Almost Prime.
FORMULA
Product p_i^e_i with Sum e_i = 11.
a(n) ~ 3628800n log n / (log log n)^10. - Charles R Greathouse IV, May 06 2013
MATHEMATICA
Select[Range[9000], Plus @@ Last /@ FactorInteger[ # ] == 11 &] (* Vladimir Joseph Stephan Orlovsky, Apr 23 2008 *)
Select[Range[30000], PrimeOmega[#]==11&] (* Harvey P. Dale, Jul 13 2013 *)
PROG
(PARI) k=11; start=2^k; finish=30000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v
(PARI) is(n)=bigomega(n)==11 \\ Charles R Greathouse IV, Oct 15 2015
CROSSREFS
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), this sequence (r = 11), A069273 (r = 12), A069274 (r = 13), A069275 (r = 14), A069276 (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: A353409 A222526 A035892 * A234881 A220584 A195069
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Mar 12 2002
STATUS
approved