login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A175431 Numbers m such that sigma(m) is not a nontrivial power, i.e., sigma(m) = A000203(n) is not equal a^b where a and b are greater than 1. 1
1, 2, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Complement of A065496.

A175432(a(n)) = 1 for n >= 1.

LINKS

Table of n, a(n) for n=1..72.

EXAMPLE

Number 3 is not in sequence because sigma(3) = 4 = 2^2.

CROSSREFS

Sequence in context: A323455 A133398 A138836 * A059921 A062289 A172284

Adjacent sequences:  A175428 A175429 A175430 * A175432 A175433 A175434

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, May 10 2010

EXTENSIONS

Extended by Ray Chandler, Aug 20 2010

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 19 00:04 EDT 2021. Contains 345125 sequences. (Running on oeis4.)