# [seqfan] Q regarding comment in A000079 (Powers of 2)

lajos66 at t-online.hu lajos66 at t-online.hu
Mon Jun 29 11:13:16 CEST 2009


Hungary:
http://hu.wikipedia.org/wiki/Vari%C3%A1ci%C3%B3

* Az n db. elem k-ad osztályú variációinak száma
(jelölje V_n^k):
V_n^k = \frac{n!}{(n-k)!} = n(n-1)\ldots (n-k+1)
.
* Az n db. elem k-ad osztályú ismétléses variációinak
száma (jelölje V_n^{k,i}):
V_n^{k,i} = n^k

example, there :Two element
* aa
* ab
* ba
* bb
2^2= 4

example, there :Three (3) element

aaa, bbb, ccc, abc, acb, bac, bca, cab, cba, aab, aba,baa,
aac, aca, caa, abb, bab, bba, bbc, bcb, cbb. acc, cac, cca,
bcc, cbc, bcc. >>27

3^3= 27

4^4 = 64,  etc...

Dátum: Wed, 24 Jun 2009 16:20:05 +1000
Feladó: Joerg Arndt <arndt at jjj.de>
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Tárgy: [seqfan] Re: Q regarding comment in A000079
(Powers of 2)

* Joerg Arndt <arndt at jjj.de> [Jun 24. 2009 15:54]:
> > [...]

Sloppy me, in

> %C A000079 Permutations of n+1 elements where no element
is more
>  than one position left of its original place. For
example, there
>  are 4 such permutations of three elements: 123, 132,
213, and
>  312. The 8 such permutations of four elements are
1234, 1243,
>  1324, 1423, 2134, 2143, 3124, and 4123. [From Joerg
>  Arndt (arndt(AT)jjj.de), June 24 2009]
>

it should be:

>  than one position RIGHT of its original place. For
example, there
^^^^^
was: "left"

Dammit.

>
> >
> > Several other comments are not top quality either (or
are at least
> > obfuscating):
> > [...]
>
> I'd suggest to kill all of these, but leave it to someone
else.
>

I'll correct my mistake should it appear as submitted,
and also murder the "not top quality" comments you
mentioned.

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