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A108775 a(n) = floor(sigma(n)/n). 7
1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
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

a(n) = floor(A017665(n)/A017666(n)). - Michel Marcus, Sep 18 2015

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

Cf. A000203, A054024.

Cf. A017665, A017666.

Sequence in context: A107577 A073700 A226957 * A300826 A305936 A211111

Adjacent sequences:  A108772 A108773 A108774 * A108776 A108777 A108778

KEYWORD

nonn

AUTHOR

Franz Vrabec, Jun 27 2005

EXTENSIONS

More terms from Robert G. Wilson v, Jun 28 2005

STATUS

approved

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Last modified October 17 05:23 EDT 2018. Contains 316275 sequences. (Running on oeis4.)