Number of compositions of n into Fibonacci numbers considering also the extension.

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Davide Rotondo

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Nov 29, 2025, 11:26:09 AM (6 days ago) Nov 29
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Hi to all dear seqfans. What I proposed to you today is an old interest for me. I didn't find anything matching in OEIS with this sequence so I hope you will find it interesting.


Fibonacci sequence and the extension



…,-21,13,-8,5,-3,2,-1,1,0,1,1,2,3,5,8,13,21,...


how many times does the value appear


-21=1

-8=1

-3=1

-1=1

0=1

1=3

2=2

3=1

5=2

8=1

13=2

21=1


right to left: a(n) = a(n-1)*3 + a(n-2)*2 + a(n-3) + a(n-5)*2 + a(n-8) + a(n-13)*2 + a(n-21)+ …


and left to right:


a(n) = a(n+1) + a(n+3) + a(n+8) + a(n+21) + … 


i don’t know but in this case a(n +/- 0) i considered that the value must be multiplied by 2


the sequence


1,8,54,468,3150,...


All the best

Davide



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