[seqfan] Re: Fwd: Problems with A072229

[Maximilian Hasler]

concerning that sequence,
A072229
  	 	 Witt index of the standard bilinear form <1,1,1,...,1> over the
2-adic rationals.
0, 0, 0, 0, 1, 2, 3, 4, 4, 4, 4, 5, 6, 7, 8, 8, 8, 8, 9, 10, 11, 12,
12, 12, 12, 13, 14, 15, 16

I agree that the author must have meant
a(n) = 4 floor( n/7 ) + [0,0,0,0,1,2,3][ n % 7 + 1]

But I don't understand the kw "more", given this formula (and the
keyword "easy" ... !)

Maximilian


On Mon, Apr 13, 2009 at 1:49 PM,  <franktaw at netscape.net> wrote:
> There are some problems with your sequence A072229.  You gave the
> formula:
>
> a(n) = n/2 + (0, 0, 0, 0, 1, 2, 3, 4) depending on residue of n mod 8.
>
>
> But if n/2 means floor(n/2), this would make the sequence start:
>
> 0,0,1,1,3,4,6,7
>
> instead of 0,0,0,0,1,2,3,4.  I would guess that what you want is
> actually 4*floor(n/8) + ....
>
> Furthermore, the terms shown do not match this formula: there is one
> less of each multiple of 4 than there should be.  In other words, what
> is actually present is:
>
> 4*floor(n/7) + (0, 0, 0, 0, 1, 2, 3)[n mod 7].
>
> I don't know anything about bilinear forms, so I can't tell if it is
> the formula or the values that is incorrect.
>
>
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