A110007 - OEIS

A110007

a(n) = n-F(F(F(n))) where F(x)=A120613(x)=floor(phi*floor(x/phi)) and phi=(1+sqrt(5))/2.

1, 2, 3, 4, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5, 5, 4, 5, 4, 5, 5, 4, 5, 4, 4, 5, 4, 5

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OFFSET

1,2

COMMENTS

To build the sequence start from the infinite Fibonacci word: b(k)=floor(k/phi)-floor((k-1)/phi) for k>=1 giving 0,1,0,1,1,0,1,0,1,1,0,1,1,0,1,0,1,1,..... Then replace each 0 by the block {4,5,4} and each 1 by the block {5,5,4,5,4}. Append the initial string {1,2,3,4}.

REFERENCES

Benoit Cloitre, On properties of irrational numbers related to the floor function, in preparation, 2005.

LINKS

Table of n, a(n) for n=1..105.

MATHEMATICA

Join[{1, 2, 3, 4}, Flatten[Table[Floor[k/GoldenRatio]-Floor[(k-1)/ GoldenRatio], {k, 30}]/.{0->{4, 5, 4}, 1->{5, 5, 4, 5, 4}}]] (* Harvey P. Dale, Dec 12 2017 *)

PROG

(PARI) F(x)=floor((1+sqrt(5))/2*floor((-1+sqrt(5))/2*x))

a(n)=n-F(F(F(n)))

CROSSREFS

Cf. A005614 (infinite Fibonacci binary word), A120613.

Cf. sequences for a(n) = n-F^k(n): A003842 (k=1), A110006 (k=2), A110010 (k=4), A110011 (k=5).

Sequence in context: A036371 A036370 A005208 * A327715 A306574 A088527

Adjacent sequences: A110004 A110005 A110006 * A110008 A110009 A110010

KEYWORD

nonn,easy

AUTHOR

Benoit Cloitre, Sep 02 2005

STATUS

approved