[seqfan] Re: Lack-a-day

[Ron Hardin]

Sure it occurs in the real world.

2 2 2 8 18 50 128 338 882 2312 6050 15842 41472 108578 284258

(n=1..) is half the number of nX2 binary arrays with no element equal to a 
strict majority of its diagonal and antidiagonal neighbors,

which itself is twice A007598(n-1).  (If I've copied out all the factors of two 
correctly)

 rhhardin at mindspring.com
rhhardin at att.net (either)



----- Original Message ----
> From: Richard Guy <rkg at cpsc.ucalgary.ca>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Sent: Thu, December 2, 2010 1:13:13 PM
> Subject: [seqfan]  Lack-a-day
> 
> Dear all,
>           I'm very discouraged at the way  OEIS
> is going.  I suppose it's just the inevitability
> of my old  age.  Here is a (final?) contribution,
> though recent experience suggests  that no-one
> will take any notice.
> 
>            It seems to me (though my Mother always
> told me that I'm not a good looker!)  that there
> is nothing under A007598 except the bare sequence.
> Or is that  all I'm allowed to see these days?
> 
>            It's a divisibility sequence.  It is
> a third order recurring sequence  with characteristic
> polynomial    x^3 - 2x^2 - 2x + 1,
>               roots -1, tau^2, 1/tau^2
> generating  function  x(1-x)/(1-2x-2x^2+x^3)
> 
>            And there must be occurrences in the real
> world?
> 
>            Goodbye!  It was fun while it lasted.   R.
> 
> 
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