# Number of m such that n=0 Mod UnitarySigma(m)

koh zbi74583.boat at orange.zero.jp
Wed Jul 23 06:19:00 CEST 2008

```    Neil

The sequence is not related with that equation.
I will soon submit it.

Yasutoshi

Dear Neil and SeqFans,

Here is a question about the Welcome page, under Referencing the OEIS.

Why not suggest that, when referencing an OEIS sequence in an article, the
name of the sequence's author should be included in the citation?

For example, the citation for A007970 could be something like:

J. H. Conway, Sequence A007970, The On-Line Encyclopedia of Integer
Sequences (2008), N. J. A. Sloane (Ed.); published electronically at
http://www.research.att.com/~njas/sequences/A007970.

This would agree with citations both for entries in MathWorld (not all of
which are authored by E. W. Weisstein) and for Problems in the Monthly, both
of which include the author's name.

Best regards,
Jonathan Sondow

> Hi, Seqfans.

> b(n) = Number of m such that n=0 Mod UnitarySigma(m)
> b(n) : 1,1,2,2,2,3,1,3,3,3,1,5,1,2,4,3,2,5,1,5

> Ex : 6=0 Mod UnitarySigma(m) , m=1,2,5, so, b(6)=3

Perhaps I don't understand this correctly, but I get b(12)=6 and you
have b(12)=5

UnitarySigma(1)=1
UnitarySigma(2)=3
UnitarySigma(3)=4
UnitarySigma(5)=6
UnitarySigma(6)=12
UnitarySigma(11)=12

giving me 6 values of m : 12==0 Mod UnitarySigma(m)

Also, if I understand correctly, b(n) is inverse moebius transform of
A063974
http://www.research.att.com/~njas/sequences/A063974
and begins 1, 1, 2, 2, 2, 3, 1, 3, 3, 3, 1, 6, 1, 2, 3, 3, 2, 6, 1, 6, 2...

(not in EIS)

...

> 5 < b(300) = 14

I get b(300)=27

> Yasutoshi

Christian

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