OFFSET
1,6
COMMENTS
The sequence is unbounded. - Vrabec
First occurrence of k: 1,6,120,27720,..., which is A023199. - Robert G. Wilson v, Jun 28 2005
a(n) > 1 if n is perfect or abundant. a(n) = 2 if n is perfect or primitive abundant (see A091191). - Alonso del Arte, Feb 06 2012
REFERENCES
W. Sierpinski, Elementary Theory of Numbers, 1987, p. 174 ff.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(6) = 2 because sigma(6)/6 = (1 + 2 + 3 + 6)/6 = 2.
MATHEMATICA
Table[ Floor[ DivisorSigma[1, n]/n], {n, 105}] (* Robert G. Wilson v, Jun 28 2005 *)
PROG
(Haskell)
a108775 n = div (a000203 n) n -- Reinhard Zumkeller, Mar 23 2013
(PARI) a(n) = sigma(n)\n; \\ Michel Marcus, Sep 18 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Franz Vrabec, Jun 27 2005
EXTENSIONS
More terms from Robert G. Wilson v, Jun 28 2005
STATUS
approved