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Zeckendorf's theorem (Theorem)

Theorem. Every positive integer can be represented as a sum of distinct Fibonacci numbers in a unique way.

This is Zeckendorf's theorem, first formulated by Edouard Zeckendorf.

For our purposes here, define the Fibonacci sequence thus: $ F_0 = 1$, $ F_1 = 1$ and $ F_m = F_{m - 2} + F_{m - 1}$ for all $ m > 0$. 1 and 1 are not distinct even though the first is $ F_0$ and the latter is $ F_1$.

A consequence of the theorem is that for every positive integer $ n$ there is a unique ordered tuplet $ Z$ consisting of $ k$ elements, all 0s or 1s, such that

$\displaystyle \sum_{i = 1}^k Z_iF_i = n,$
where $ Z_i$ is the $ i$th element in $ Z$. This ordered tuplet $ Z$ is the Zeckendorf representation of $ n$, or we might even say the Fibonacci base representation of $ n$ (or the Fibonacci coding of $ n$).

So for example, 53 = 34 + 13 + 5 + 1, that is, $ F_8 + F_6 + F_4 + F_1$. Furthermore, $ Z = (1, 0, 1, 0, 1, 0, 0, 1)$. We list the constituent elements in descending order from $ Z_k$ to $ Z_1$ to facilitate reinterpretation as a binary integer, 10101001 (or 169) in this example. Taking the Zeckendorf representations of integers in order and reinterpreting in binary as

$\displaystyle \sum_{i = 1}^k Z_i2^{i - 1}$
gives the sequence 1, 2, 4, 5, 8, 9, 10, 16, 17, 18, 20, 21, 32, 33, 34, ... (A003714 in Sloane's OEIS). It can be observed that these numbers have no consecutive 1s in their binary representations.

Bibliography

1
J. Tatersall, Elementary number theory in nine chapters Cambridge: Cambridge University Press (2005): 44
2
J.-P. Allouche, J. Shallit and G. Skordev, ``Self-generating sets, integers with missing blocks and substitutions" Discrete Math., 292 (2005): 1 - 15



"Zeckendorf's theorem" is owned by CompositeFan.
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See Also: Fibonacci sequence

Other names:  Zeckendorff's theorem
Also defines:  Zeckendorf representation, Fibonacci base, Fibonacci coding

Attachments:
proof that every positive integer has a Zeckendorf representation (Proof) by PrimeFan
proof that the Zeckendorf representation of a positive integer is unique (Proof) by PrimeFan
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Cross-references: consecutive, numbers, OEIS, sequence, order, binary, descending order, representation, ordered tuplet, consequence, Edouard Zeckendorf, Fibonacci numbers, sum, integer, positive
There are 4 references to this entry.

This is version 7 of Zeckendorf's theorem, born on 2006-07-01, modified 2007-01-24.
Object id is 8120, canonical name is ZeckendorfsTheorem.
Accessed 3631 times total.

Classification:
AMS MSC11B39 (Number theory :: Sequences and sets :: Fibonacci and Lucas numbers and polynomials and generalizations)
 11A63 (Number theory :: Elementary number theory :: Radix representation; digital problems)

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