[seqfan] Re: Lack-a-day
Ron Hardin
rhhardin at att.net
Thu Dec 2 19:28:44 CET 2010
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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