[seqfan] Re: Two neighbors sum -- and odd ranks in S

Reinhard Zumkeller reinhard.zumkeller at gmail.com
Wed Oct 22 20:23:20 CEST 2014


Thanks for your understanding (and implicit encouragement).
Now I added a program, neither nice nor magic, but at least I could confirm
Alois' b-file and add the inverse permutation:
https://oeis.org/draft/A245057

Concerning Max' conjecture:
Smallest m such that abs(a(m)-m) = n:
[2,0,6,122,922,1994,3986,29618,59234,... ? ? ]

Best regards
Reinhard


2014-10-22 18:25 GMT+02:00 M. F. Hasler <oeis at hasler.fr>:

> > No need to apologize!  It's amazing to me that Haskell programs run at
> all
> > - magic!
>
> I agree with both statements. :-)
>
> Reinhard, I had indeed a similar but in a first version of my program,
> which I cured by making sure that as soon as some a(n) is fixed (in
> particular also a(2k)), then I "reserve" the value a(n-1)+a(n) as well
> as a(n)+a(n+1) in case the latter already is defined. I think that not
> doing the second part led to duplicate values.
>
> Thanks to Alois for the big b-file which yields a graph that is almost
> a straight line.
> I think one can establish a very small bound for d(n) = a(n)-n:
> it seems that values d(n) = k > 0 occur first around  n ~ 1000*2^(k-4)
> (for k>3),
> and the value -k then occurs first at index n+2k-1 (for all k>0 !?).
>
> (I added this as comment to http://oeis.org/A249129 .)
>
> --Maximilian
>
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