OFFSET
1,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..8822
Vaclav Kotesovec, Plot of a(n)/n for n = 1..8000
FORMULA
a(n) seems to be asymptotic to c*n with c=4.8....
MATHEMATICA
Select[Range[300], Not[Divisible[DivisorSigma[1, #!], # + 1]] &] (* Vaclav Kotesovec, Feb 16 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Dec 05 2002
STATUS
approved