This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A069272 11-almost primes (generalization of semiprimes). 31
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Product of 11 not necessarily distinct primes. Divisible by exactly 11 prime powers (not including 1). 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 = 11. a(n) ~ 3628800n log n / (log log n)^10. - Charles R Greathouse IV, May 06 2013 MATHEMATICA Select[Range, Plus @@ Last /@ FactorInteger[ # ] == 11 &] (* Vladimir Joseph Stephan Orlovsky, Apr 23 2008 *) Select[Range, 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: A289476 A222526 A035892 * A234881 A220584 A195069 Adjacent sequences:  A069269 A069270 A069271 * A069273 A069274 A069275 KEYWORD nonn AUTHOR Rick L. Shepherd, Mar 12 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 18 00:09 EDT 2019. Contains 328135 sequences. (Running on oeis4.)