OFFSET
1,2
COMMENTS
The quotient (sigma(k+1)/sigma(k)) is equal to 1, 2, 3, 4 or 5 for the first 5000 terms. - Donovan Johnson, Oct 21 2012
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..5000
EXAMPLE
5 is included because sigma(5) = 6 divides sigma(6) = 12.
MATHEMATICA
Select[Range[10^5], Divisible[DivisorSigma[1, # + 1], DivisorSigma[1, #]] &] (* Michael De Vlieger, Sep 03 2017 *)
PROG
(PARI) isok(n) = !(sigma(n+1) % sigma(n)); \\ Michel Marcus, Sep 04 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Nov 11 2000
EXTENSIONS
More terms from Benoit Cloitre, Jul 27 2002
STATUS
approved