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Definition 6.1   A pattern of length maths where maths, i.e. maths will be referred as a "nothing but maths" pattern, and a pattern of length maths where maths will be referred as an "any, one, one" pattern (the sequence maths must be palindromic, since maths has to be so).

Proposition 6.2   A "nothing but ones" is known to be a pattern of second kind for all length maths (from theorem 4.10). When maths, the corresponding maths and maths are given by:

maths (6.1)

where maths. Additionally, the parameter maths must be even when maths.

Proof. We have maths, where maths is the maths-th Fibonacci number. Thus the signatures are given by:

maths

and criterion of corollary 4.11 is satisfied (when maths, maths is also a pattern of first kind and the parity condition over maths is here to select the maths). The formulae

maths

are straightforward. Finally, 6.1 is an asymptotic formula, based upon

maths

It can be checked that 6.1 holds from maths, while the empty pattern occurs when maths. maths

Proposition 6.3   A "nothing but fours" pattern is a pattern of first kind for all length maths, and maths can ever be additionally required. In such a case, we have:

maths (6.2)

where maths.

Proof. We have maths, where maths is defined by maths and maths. Thus the signatures are alternatively maths and maths and criterion of theorem 4.10 (cor. 4.12) is satisfied. Formulae

maths

are straightforward and lead to maths. Finally, 6.2 is an asymptotic formula, based upon

maths

In fact, 6.2 holds from the beginning. maths

Remark 6.4   We have therefore proven that it exists an infinite number of quadratic integers of each kind having a given period length. But the maths and maths found are quickly huge, and give no hint about the smallest maths having a given period length.

Remark 6.5  

Since maths, we have maths when maths. In other words, when the maths-pattern is maths "4", the maths-pattern is maths "1", and the length of the maths period is exactly three times the length of the maths period.

Proposition 6.6   An "any, one, one" pattern is known from theorem 4.10 to be a pattern of second kind if and only if its middle element is odd or none. In such a case, all the maths associated to a maths belong to the same pattern of first kind maths, where maths. And we have

maths

Conversely, if a pattern maths where all maths are even and at least maths belongs to some maths such that maths is even, then all such maths share also the above described maths as pattern of second kind.

Proof. An "any, one, one" pattern is the product of one matrix maths and several matrices maths where

maths

The value of the maths pattern follows from :

maths

proving that maths is a fixed point of maths when maths is a fixed point of maths. Conversely, if maths is a fixed point of maths and maths as described, then maths is a pattern, maths is odd and maths is a fixed point of maths. maths

Definition 6.7   The alternate pattern maths is defined by maths when maths and, otherwise, by maths. The pseudo period of maths is the period associated to maths, i.e one or three (ordinary) periods of maths.

If we plot the period of maths versus the pseudo-period of maths for all maths in maths, we obtain FIG. 1.1 (left : the whole figure; right: the lower left corner zoomed in).

FIG.  6.1: Period of maths versus the pseudo-period of maths.
maths maths

Fact 6.8   We have

maths

**


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2004-02-06