Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A020491
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A020491 Numbers n such that sigma_0(n) divides phi(n). +0
2
1, 3, 5, 7, 8, 9, 10, 11, 13, 15, 17, 18, 19, 21, 23, 24, 26, 28, 29, 30, 31, 33, 34, 35, 37, 39, 40, 41, 43, 45, 47, 49, 51, 52, 53, 55, 56, 57, 58, 59, 61, 63, 65, 67, 69, 70, 71, 72, 73, 74, 76, 77, 78, 79, 82, 83, 84, 85, 87, 88, 89, 90, 91, 93, 95, 97, 98, 99, 101, 102, 103, 104 (list; graph; listen)
OFFSET

1,2

MATHEMATICA

Select[ Range[ 105 ], IntegerQ[ EulerPhi[ # ]/DivisorSigma[ 0, # ] ]& ]

CROSSREFS

Sequence in context: A131903 A141114 A136443 this_sequence A047746 A111638 A080262

Adjacent sequences: A020488 A020489 A020490 this_sequence A020492 A020493 A020494

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

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 July 25 02:12 EDT 2008. Contains 142294 sequences.


AT&T Labs Research