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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A166069 Multiply perfect numbers k such that sigma(k)/k > 2. 5
120, 672, 30240, 32760, 523776, 2178540, 23569920, 45532800, 142990848, 459818240, 1379454720, 1476304896, 14182439040, 31998395520, 43861478400, 51001180160, 66433720320, 153003540480, 403031236608, 518666803200 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Subsequence of multiply perfect numbers (A007691). Numbers k = A007691(n) such that sigma(A007691(n))/A007691(n) > 2. Numbers k = A007691(n) such that A054030(n) > 2.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n=1..1587

EXAMPLE

For n = 1 the a(1) = 120, sigma(120) / 120 = 360 / 120 = 3, i.e. > 2.

CROSSREFS

Sequence in context: A100145 A090216 A113546 * A114887 A069085 A039688

Adjacent sequences:  A166066 A166067 A166068 * A166070 A166071 A166072

KEYWORD

nonn

AUTHOR

Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Oct 06 2009

EXTENSIONS

Extended by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Oct 12 2009

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 15 04:23 EST 2012. Contains 205694 sequences.