login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064052 Not sqrt(n)-smooth: some prime factor of n is > sqrt(n). 10
2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 20, 21, 22, 23, 26, 28, 29, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 51, 52, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 68, 69, 71, 73, 74, 76, 77, 78, 79, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 99, 101, 102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This set (S say) has density d(S) = Log(2) - Benoit Cloitre, Jun 12 2002

Finch defines a positive integer N to be "jagged" if its largest prime factor is > sqrt(N). - Frank Ellermann, Apr 21 2011

REFERENCES

S. R. Finch, Mathematical Constants, 2003, chapter 2.21.

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,1000

Eric Weisstein's World of Mathematics, Greatest Prime Factor

EXAMPLE

9=3*3 is not "jagged", but 10=5*2 is "jagged": 5 > sqrt(10).

20=5*2*2 is "jagged", but not squarefree, cf. A005117.

MATHEMATICA

Reap[For[n = 2, n <= 102, n++, f = FactorInteger[n][[All, 1]]; s = Sqrt[n]; If[Count[f, p_ /; p > s] > 0, Sow[n]]]][[2, 1]] (* Jean-Fran├žois Alcover, May 16 2014 *)

PROG

(PARI) { n=0; for (m=2, 10^9, f=factor(m)~; if (f[1, length(f)]^2 > m, write("b064052.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith, Sep 06 2009]

CROSSREFS

Cf. A048098, A063538, A063539.

Sequence in context: A247180 A048839 A122144 * A248792 A064594 A240370

Adjacent sequences:  A064049 A064050 A064051 * A064053 A064054 A064055

KEYWORD

nonn,easy

AUTHOR

Dean Hickerson, Aug 28 2001

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified December 20 03:43 EST 2014. Contains 252241 sequences.