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!)
A237287 Numbers that are not practical: positive integers n such that there exists at least one number k <= sigma(n) that is not a sum of distinct divisors of n. 7
3, 5, 7, 9, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 26, 27, 29, 31, 33, 34, 35, 37, 38, 39, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 65, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 79, 81, 82, 83, 85, 86, 87, 89, 91, 92, 93, 94 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Complement of A005153 (practical numbers).

Numbers n such that A030057(n) < n.

First differs from A237046 at a(48).

First differs from A238524 at a(55). - Omar E. Pol, Mar 09 2014

LINKS

Jaroslav Krizek, Table of n, a(n) for n = 1..5000

EXAMPLE

5 is in the sequence because there are 3 numbers <= sigma(5) = 6 that are not a sum of any subset of distinct divisors of 5: 2, 3 and 4.

CROSSREFS

Cf. A000203, A005153, A237046, A237289, A237290.

Sequence in context: A231564 A325798 A238524 * A237046 A076212 A085621

Adjacent sequences:  A237284 A237285 A237286 * A237288 A237289 A237290

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Mar 02 2014

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 May 16 08:07 EDT 2021. Contains 343940 sequences. (Running on oeis4.)