A135401, A000898

[Maximilian Hasler]

I'm maybe a bit tired and miss something obvious, but the definition of
http://www.research.att.com/~njas/sequences/A135401
seems to indicate that one can simply choose any list of [n/2] numbers among
{1...n} \ {(n+1)/2} for p(1)...p([n/2]) and the remaining values of p
are given by
the formula p(k) = n+1-p(n+1-k),
This would mean
A135401(n)=binomial(n\2*2,n\2)
vector(20,n,A135401(n)) = [1, 2, 2, 6, 6, 20, 20, 70, 70, 252, 252,
924, 924, 3432, 3432, 12870, 12870, 48620, 48620, 184756]

but instead of 70 there is 76 given in the current version.

Maximilian

On Jan 20, 2008 10:12 AM, Leroy Quet <q1qq2qqq3qqqq at yahoo.com> wrote:
> Does A135401(n) = A000898(floor(n/2)), for n =
> all positive integers?
>
> The rook problem on an n-by-n chessboard, as I
> understand it, is directly connected to
> permutations of (1,2,3,...n).
> So maybe the connection between these two
> sequences is obvious.
>
>
> Thanks,
> Leroy Quet
>
>
>
>
>
> \/\/\/\///////\\\\\\\/\/\/\/
> /\/\/\///////**\\\\\\\/\/\/\
> \/\/\///////*/\*\\\\\\\/\/\/
> /\/\/\\\\\\\*\/*///////\/\/\
> \/\/\/\\\\\\\**///////\/\/\/
> /\/\/\/\\\\\\\///////\/\/\/\
>
>
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-- 
Maximilian F. Hasler (Maximilian.Hasler(AT)gmail.com)