login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A069278 17-almost primes (generalization of semiprimes). 28
131072, 196608, 294912, 327680, 442368, 458752, 491520, 663552, 688128, 720896, 737280, 819200, 851968, 995328, 1032192, 1081344, 1105920, 1114112, 1146880, 1228800, 1245184, 1277952, 1492992, 1507328, 1548288, 1605632, 1622016 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Product of 17 not necessarily distinct primes.
Divisible by exactly 17 prime powers (not including 1).
For n = 1..2628 a(n)=2*A069277(n). - Zak Seidov, Jun 25 2017
LINKS
Eric Weisstein's World of Mathematics, Almost Prime.
FORMULA
Product p_i^e_i with Sum e_i = 17.
MATHEMATICA
Select[Range[2*10^6], PrimeOmega[#]==17&] (* Harvey P. Dale, Sep 28 2016 *)
PROG
(PARI) k=17; start=2^k; finish=2000000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v
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), A069272 (r = 11), A069273 (r = 12), A069274 (r = 13), A069275 (r = 14), A069276 (r = 15), A069277 (r = 16), this sequence (r = 17), A069279 (r = 18), A069280 (r = 19), A069281 (r = 20). - Jason Kimberley, Oct 02 2011
Sequence in context: A069392 A289479 A222529 * A190780 A017698 A010805
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Mar 13 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 02:46 EDT 2024. Contains 370952 sequences. (Running on oeis4.)