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A005375 a(n)=n-a(a(a(a(n-1)))).
(Formerly M0458)
4
0, 1, 1, 2, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 10, 11, 11, 12, 13, 14, 15, 15, 16, 17, 18, 19, 19, 20, 20, 21, 22, 23, 24, 24, 25, 25, 26, 27, 27, 28, 29, 30, 31, 31, 32, 32, 33, 34, 34, 35, 36, 37, 37, 38, 39, 40, 41, 41, 42, 42, 43, 44, 44, 45, 46, 47, 47, 48, 49, 50, 51, 51, 52, 53 (list; graph; refs; listen; history; internal format)
OFFSET

0,4

COMMENTS

Rule of construction for the sequence: a(n) = An, where An denotes the Lam{\'}e antecessor to (or right shift of) n, which is found by replacing each Lm(i) (Lm(n) = Lm(n-1) + Lm(n-4): A003269) in the Zeckendorffian expansion (obtained by repeatedly subtracting the largest Lam{\'}e number you can until nothing remains) by Lm(i-1) (A1=1). For example: 58 = 50 + 7 + 1, so a(58)= 36 + 5 + 1 = 42. - Diego Torres (torresvillarroel(AT)hotmail.com), Nov 24 2002

a(A194081(n)) = n and a(m) <> n for m < A194081(n). [Reinhard Zumkeller, Aug 17 2011]

REFERENCES

D. Hofstadter, "Goedel, Escher, Bach", p. 137.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Nick Hobson, Python program for this sequence

Index entries for Hofstadter-type sequences

Index entries for sequences from "Goedel, Escher, Bach"

FORMULA

Conjecture: a(n) = floor(c*n) + 0 or 1, where c is the positive real root of x^4+x-1 = 0, c=0.724491959000515611588372282... - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 05 2002

MAPLE

H:=proc(n) option remember; if n=1 then 1 else n-H(H(H(H(n-1)))); fi; end proc;

MATHEMATICA

a[0] := 0; a[n_] := a[n] = a[n] = n - a[a[a[a[n - 1]]]]; Table[a[n], {n, 0, 73}] (* From Alonso del Arte, Aug 17 2011 *)

PROG

(Haskell)

a005375 n = a005375_list !! n

a005375_list =  0 : 1 : zipWith (-)

   [2..] (map a005375 (map a005375 (map a005375 (tail a005375_list))))

-- Reinhard Zumkeller, Aug 17 2011

CROSSREFS

Sequence in context: A198454 A063882 A097873 * A138370 A125051 A064067

Adjacent sequences:  A005372 A005373 A005374 * A005376 A005377 A005378

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 12 2000

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Last modified February 16 21:51 EST 2012. Contains 205978 sequences.