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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A079879 Median prime factor: a(1)=1 and for n>1: least prime p such that not more than floor(Omega(n)/2) prime factors are greater p; Omega(n) is the total number of prime factors of n (A001222). 2
1, 2, 3, 2, 5, 2, 7, 2, 3, 2, 11, 2, 13, 2, 3, 2, 17, 3, 19, 2, 3, 2, 23, 2, 5, 2, 3, 2, 29, 3, 31, 2, 3, 2, 5, 2, 37, 2, 3, 2, 41, 3, 43, 2, 3, 2, 47, 2, 7, 5, 3, 2, 53, 3, 5, 2, 3, 2, 59, 2, 61, 2, 3, 2, 5, 3, 67, 2, 3, 5, 71, 2, 73, 2, 5, 2, 7, 3, 79, 2, 3, 2, 83, 2, 5, 2, 3, 2, 89, 3, 7, 2, 3, 2, 5, 2 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

A020639(n)<= a(n)<=A006530(n);

a(m)=A020639(m)=A006530(m) iff m is a prime power (A000961).

EXAMPLE

a(30)=a(2*3*5)=3; a(60)=a(2*2*3*5)=2; a(72)=a(2*2*2*3*3)=2; a(90)=a(2*3*3*5)=3; a(108)=a(2*2*3*3*3)=3; a(144)=a(2*2*2*2*3*3)=2; a(216)=a(2*2*2*3*3*3)=2.

CROSSREFS

Cf. A033676, O000002, A079880, A079881.

Sequence in context: A092028 A020639 A092067 * A071889 A091963 A067695

Adjacent sequences:  A079876 A079877 A079878 * A079880 A079881 A079882

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 13 2003

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

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

Last modified February 16 15:50 EST 2012. Contains 205931 sequences.