OFFSET
1,1
COMMENTS
A subset of A045770.
If p=2^m-9 is prime (m is in the sequence A059610) then n=2^(m-1)*p is in the sequence. See comment lines of the sequence A088831. 56, 368, 128768, 2087936 & 8589344768 are of the mentioned form. - Farideh Firoozbakht, Feb 15 2008
a(28) > 10^12. - Donovan Johnson, Dec 08 2011
a(31) > 10^13. - Giovanni Resta, Mar 29 2013
a(38) > 10^18. - Hiroaki Yamanouchi, Aug 23 2018
Any term x of this sequence can be combined with any term y of A125247 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable. - Timothy L. Tiffin, Sep 13 2016
LINKS
Giovanni Resta and Hiroaki Yamanouchi, Table of n, a(n) for n = 1..37 (terms a(1)-a(30) from Giovanni Resta)
EXAMPLE
Except first 2 terms of A045770 (10 and 49) are here:abundances={-2,-41,8,8,8,8,8,8,8,8,8,8,8,8,8}.
MATHEMATICA
Do[If[DivisorSigma[1, n]==2n+8, Print[n]], {n, 100000000}] (* Farideh Firoozbakht, Feb 15 2008 *)
PROG
(PARI) is(n)=sigma(n)==2*n+8 \\ Charles R Greathouse IV, Feb 21 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 28 2003
EXTENSIONS
a(14)-a(17) from Farideh Firoozbakht, Feb 15 2008
a(18)-a(25) from Donovan Johnson, Dec 23 2008
a(26)-a(27) from Donovan Johnson, Dec 08 2011
STATUS
approved