|
| |
|
|
A033987
|
|
Numbers that are divisible by at least 4 primes (counted with multiplicity).
|
|
9
| |
|
|
16, 24, 32, 36, 40, 48, 54, 56, 60, 64, 72, 80, 81, 84, 88, 90, 96, 100, 104, 108, 112, 120, 126, 128, 132, 135, 136, 140, 144, 150, 152, 156, 160, 162, 168, 176, 180, 184, 189, 192, 196, 198, 200, 204, 208, 210, 216, 220, 224, 225, 228, 232, 234, 240, 243
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Complement of A037144: A001222(a(n))>3; A117358(a(n))>1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 10 2006
Also numbers such that no permutation of all proper divisors exists with coprime adjacent elements: A178254(a(n))=0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 24 2010]
|
|
|
LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000
|
|
|
FORMULA
| Product p_i^e_i with Sum e_i >= 4.
A001055(a(n))>A033273(a(n)). [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 09 2009]
|
|
|
CROSSREFS
| Cf. A014613.
Cf. A001055, A033273. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 09 2009]
Subsequence of A033942; A178212 is a subsequence. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 24 2010]
Sequence in context: A105732 A166319 A114415 * A140349 A088493 A074451
Adjacent sequences: A033984 A033985 A033986 * A033988 A033989 A033990
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
|
|
|
EXTENSIONS
| More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1998.
|
| |
|
|
