Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A115958
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A115958 Numbers n having exactly 4 distinct prime factors, the largest of which is greater than or equal to sqrt(n) (i.e. sqrt(n)-rough numbers with exactly 4 distinct prime factors). +0
6
930, 1110, 1230, 1290, 1410, 1590, 1770, 1806, 1830, 1974, 2010, 2130, 2190, 2226, 2370, 2478, 2490, 2562, 2670, 2814, 2910, 2982, 3030, 3066, 3090, 3210, 3270, 3318, 3390, 3486, 3660, 3738, 3810, 3930, 4020, 4074, 4110, 4170, 4242, 4260, 4326, 4380 (list; graph; listen)
OFFSET

1,1

EXAMPLE

3660 is in the sequence because it has 4 distinct prime factors

(2, 3, 5, and 61) and 61>sqrt(3660).

MAPLE

with(numtheory): a:=proc(n) if nops(factorset(n))=4 and factorset(n)[4]^2>=n then n else fi end: seq(a(n), n=1..4500);

CROSSREFS

Cf. A115956, A115957, A115959, A115960, A115961.

Sequence in context: A074889 A109184 A068651 this_sequence A035856 A093231 A105213

Adjacent sequences: A115955 A115956 A115957 this_sequence A115959 A115960 A115961

KEYWORD

nonn

AUTHOR

Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 02 2006

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified November 18 20:14 EST 2008. Contains 147244 sequences.


AT&T Labs Research