[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>
    Válaszcím: Sequence Fanatics Discussion list
    <seqfan at list.seqfan.eu>
    Címzett: Sequence Fanatics Discussion list
    <seqfan at list.seqfan.eu>
    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

    > Added this one:
    > %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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