Multiplicative order not
Max Alekseyev
maxale at gmail.com
Thu Jun 5 07:13:04 CEST 2008
On Wed, Jun 4, 2008 at 6:07 PM, koh <zbi74583 at boat.zero.ad.jp> wrote:
>> In general, I can prove that either A137605(n) = A002326(n-1) - 1, or
>> A137605(n) = A002326(n-1)/2 - 1.
>> But at the moment I don't see an efficient way to determine which case
>> is taking place.
>>
> My understanding is the following.
> If b(n-1) is odd then b(n)=k-(b(n-1)+1)/2
> 2*b(n)=2*k-b(n-1)-1
> 2*b(n)=-b(n-1) Mod 2*k-1
> b(n)=-b(n-1)/2 Mod 2*k-1
>
> If the signature "-1" doesn't exist then A137605(n) = A002326(n) - 1
>
> Indeed it exists.
> The smallest case of A137605(n) = A002326(n)/2 - 1.
> The existence of coefficient "1/2" depends on number of the signature.
Actually, it depends on the oddness of the number of -1's. If the
number of -1's is odd then there is the coefficient 1/2 in the
formula. But it seems to be no apparent way to compute this number (or
just its oddness) without computing the whole sequence of b()'s.
Regards,
Max
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