The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A200981

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A200981

Numbers n such that the sum of non-divisors of n is prime.
(history; published version)

#12 by Charles R Greathouse IV at Sun Aug 03 14:01:36 EDT 2014

MATHEMATICA

okQ[n_] := (n > 0) && PrimeQ[n]; Select[Range[1000], okQ[# (#+1)/2 - DivisorSigma[1, #]] &] (* _T. D. Noe, _, Dec 15 2011 *)

Discussion

Sun Aug 03

14:01

OEIS Server: https://oeis.org/edit/global/2267

#11 by Russ Cox at Fri Mar 30 18:53:49 EDT 2012

AUTHOR

_Paolo P. Lava (paoloplava(AT)gmail.com), _, Dec 13 2011

Discussion

Fri Mar 30

18:53

OEIS Server: https://oeis.org/edit/global/262

#10 by T. D. Noe at Thu Dec 15 11:34:51 EST 2011

STATUS

editing

approved

#9 by T. D. Noe at Thu Dec 15 11:34:08 EST 2011

MATHEMATICA

okQ[n_] := (n > 0) && PrimeQ[n]; Select[Range[1000], okQ[# (#+1)/2 - DivisorSigma[1, #]] &] (* T. D. Noe, Dec 15 2011 *)

STATUS

approved

editing

Discussion

Thu Dec 15

11:34

T. D. Noe: Sorry, I meant n(n+1)/2 - Sigma(n).

#8 by T. D. Noe at Thu Dec 15 11:19:57 EST 2011

STATUS

proposed

approved

#7 by Paolo P. Lava at Wed Dec 14 03:12:16 EST 2011

STATUS

editing

proposed

Discussion

Thu Dec 15

11:19

T. D. Noe: In my quick research, it appears to no one, outside of these 6 sequences, uses the term antisigma. It is merely n-sigma(n), which is easier to understand than a new term.

#6 by Paolo P. Lava at Wed Dec 14 03:02:27 EST 2011

CROSSREFS

Cf. A023194, A024816,.

STATUS

approved

editing

Discussion

Wed Dec 14

03:12

Paolo P. Lava: Ok, as you like, but I used the term "antisigma" that is defined in A024816 and referenced in other 6 sequences of OEIS. To be consistent I suggest to delete it also there or leave my definition as it was. Thank.

#5 by T. D. Noe at Tue Dec 13 17:10:58 EST 2011

STATUS

editing

approved

#4 by T. D. Noe at Tue Dec 13 17:10:54 EST 2011

NAME

Numbers n such that antisigma(n) (the sum of non-divisors of n) is prime.

STATUS

proposed

editing

#3 by Paolo P. Lava at Tue Dec 13 08:02:43 EST 2011

STATUS

editing

proposed

Discussion

Tue Dec 13

11:24

T. D. Noe: According to my quick search, antisigma is not defined in the entire web.  I suggest saying what it really means instead of creating a new term.