A105083 -id:A105083 - cp's OEIS frontend

A092782 The ternary tribonacci word; also a Rauzy fractal sequence: fixed point of the morphism 1 -> 12, 2 -> 13, 3 -> 1, starting from a(1) = 1.

1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3

Offset: 1

Philippe Deléham, Apr 23 2004

See A080843 for the {0,1,2} version, which in a sense is the most basic version.
See also A103269 for another version with further references and comments.
Also called a tribonacci word. In the limit the ratios #1's : #2's : #3's are t^2 : t : 1 where t is the tribonacci constant 1.839286755... (A058265). - Frank M Jackson, Mar 29 2018
a(n)-1 is the number of trailing 0's in the maximal tribonacci representation of n (A352103). - Amiram Eldar, Feb 29 2024

			From _Joerg Arndt_, Sep 14 2013: (Start)
The first few steps of the substitution are
Start: 1
Maps:
  1 --> 12
  2 --> 13
  3 --> 1
-------------
0:   (#=1)
  1
1:   (#=2)
  12
2:   (#=4)
  1213
3:   (#=7)
  1213121
4:   (#=13)
  1213121121312
5:   (#=24)
  121312112131212131211213
6:   (#=44)
  12131211213121213121121312131211213121213121
7:   (#=81)
  121312112131212131211213121312112131212131211213121121312121312112131213121121312
(End)

This entry has a fairly complete list of references and links concerning the ternary tribonacci word. - N. J. A. Sloane, Aug 17 2018
J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003, p. 246.
Michel Rigo, Formal Languages, Automata and Numeration Systems, 2 vols., Wiley, 2014. Mentions this sequence - see "List of Sequences" in Vol. 2.

N. J. A. Sloane, Table of n, a(n) for n = 1..19513
Pierre Arnoux and Edmund Harriss, What is a Rauzy Fractal?, Notices Amer. Math. Soc., 61 (No. 7, 2014), 768-770, also p. 704 and front cover.
Scott Balchin and Dan Rust, Computations for Symbolic Substitutions, Journal of Integer Sequences, Vol. 20 (2017), Article 17.4.1.
Elena Barcucci, Luc Belanger and Srecko Brlek, On tribonacci sequences, Fib. Q., 42 (2004), 314-320. See T on page 315.
Marcy Barge and Jaroslaw Kwapisz, Geometric theory of unimodular Pisot substitutions, Amer. J. Math. 128 (2006), no. 5, 1219--1282. MR2262174 (2007m:37039). See Fig. 18.1. - _N. J. A. Sloane_, Aug 06 2014
Jean Berstel and J. Karhumaki, Combinatorics on words - a tutorial, Bull. EATCS, #79 (2003), pp. 178-228.
Nataliya Chekhova, Pascal Hubert, and Ali Messaoudi, Propriétés combinatoires, ergodiques et arithmétiques de la substitution de Tribonacci, Journal de théorie des nombres de Bordeaux, 13.2 (2001): 371-394.
David Damanik and Luca Q. Zamboni, Arnoux-Rauzy subshifts: linear recurrence, powers and palindromes, arXiv:math/0208137 [math.CO], 2002.
Aldo de Luca and Luca Q. Zamboni, On prefixal factorizations of words, arXiv:1505.02309 [math.CO], 2015. See Example 2.
Aldo de Luca and Luca Q. Zamboni, On prefixal factorizations of words, European Journal of Combinatorics, Volume 52, Part A, 2016, pp. 59-73. See Example 2.
F. Michel Dekking, Morphisms, Symbolic Sequences, and Their Standard Forms, Journal of Integer Sequences, Vol. 19 (2016), Article 16.1.1.
F. Michel Dekking, Jeffrey Shallit, and N. J. A. Sloane, Queens in exile: non-attacking queens on infinite chess boards, Electronic J. Combin., 27:1 (2020), #P1.52.
Eric Duchêne and Michel Rigo, A morphic approach to combinatorial games: the Tribonacci case. RAIRO - Theoretical Informatics and Applications, 42, 2008, pp 375-393. doi:10.1051/ita:2007039. [Also available here]
Jacques Justin and Laurent Vuillon, Return words in Sturmian and episturmian words, RAIRO-Theoretical Informatics and Applications 34.5 (2000): 343-356. See Example on page 345.
Aayush Rajasekaran, Narad Rampersad, and Jeffrey Shallit, Overpals, Underlaps, and Underpals, In: Brlek S., Dolce F., Reutenauer C., Vandomme É. (eds) Combinatorics on Words, WORDS 2017, Lecture Notes in Computer Science, vol 10432.
Gérard Rauzy, Nombres algébriques et substitutions, Bull. Soc. Math. France 110.2 (1982): 147-178. See page 148.
Victor F. Sirvent, Semigroups and the self-similar structure of the flipped tribonacci substitution, Applied Math. Letters, 12 (1999), 25-29. [Contains further related references.]
Victor F. Sirvent, The common dynamics of the Tribonacci substitutions, Bulletin of the Belgian Mathematical Society-Simon Stevin 7.4 (2000): 571-582.
Bo Tan and Zhi-Ying Wen, Some properties of the Tribonacci sequence, European Journal of Combinatorics, 28 (2007) 1703-1719.
Ondřej Turek, Abelian Complexity Function of the Tribonacci Word, J. Int. Seq. 18 (2015) Article 15.3.4.
Index entries for sequences that are fixed points of mappings.

Cf. A003144, A003145, A003146, A100619, A103269, A073058, A245553, A245554, A105083, A352103.
See A080843 for a {0,1,2} version.
First differences: A317950.

f(1):= (1, 2): f(2):= (1, 3): f(3):= (1): A:= [1]:
for i from 1 to 16 do A:= map(f, A) od:
A; # 19513 terms of A092782; A103269; from N. J. A. Sloane, Aug 06 2018

Nest[ Flatten[# /. {1 -> {1, 2}, 2 -> {1, 3}, 3 -> 1}] &, {1}, 8] (* Robert G. Wilson v, Mar 04 2005 and updated Apr 29 2018 *)

w=vector(9,x,[]); w[1]=[1];
for(n=2,9,for(k=1,#w[n-1],m=w[n-1][k];v=[];if(m-1,if(m-2,v=[1],v=[1,3]),v=[1,2]);w[n]=concat(w[n],v)));
w[9] \\ Gerald McGarvey, Dec 18 2009

strsub(s, vv, off=0)=
{
    my( nl=#vv, r=[], ct=1 );
    while ( ct <= #s,
        r = concat(r, vv[ s[ct] + (1-off) ] );
        ct += 1;
    );
    return( r );
}
t=[1];  for (k=1, 10, t=strsub( t, [[1,2], [1,3], [1]], 1 ) );  t
\\ Joerg Arndt, Sep 14 2013

A092782_vec(N,s=[[1,2],[1,3],1],A=[1])={while(#AM. F. Hasler, Dec 14 2018

a(n) = 1 for n in A003144; a(n) = 2 for n in A003145; a(n) = 3 for n in A003146.

a(n) = A080843(n-1) + 1. - Joerg Arndt, Sep 14 2013

Additional references and links added by N. J. A. Sloane, Aug 17 2018

A073058 Define s(1)={1,2}, s(2)={1,3} and s(3)={1}. For a finite sequence A={a_1, ..., a_n}, with elements in {1,2,3}, define t(A) to be the concatenation of A, s(a_1), s(a_2), ... and s(a_n). Start with the sequence {1,2,3} and repeatedly apply t; limiting sequence is shown.

Original entry on oeis.org

1, 2, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 1

Offset: 1

Roger L. Bagula, Aug 16 2002

nonn

A fractal sequence related to a sequence of Rauzy.

P. Arnoux and E. Harriss, What is a Rauzy Fractal?, Notices Amer. Math. Soc., 61 (No. 7, 2014), 768-770, also p. 704 and front cover.
Vincent Canterini and Anne Siegel, Geometric Representations of Substitutions of Pisot Type, Trans. Amer. Math. Soc. 353 (2001), 5121-5144.

Cf. A092782, A103684, A105083, A245553, A245554.

Nest[ Flatten[ Join[#, # /. {1 -> {1, 2}, 2 -> {1, 3}, 3 -> {1}}]] &, {1, 2, 3},
4] (* Robert G. Wilson v, Jan 01 2017 *)

A202342 Numbers occurring exactly twice in Hofstadter H-sequence A005374.

Original entry on oeis.org

1, 4, 5, 7, 10, 13, 14, 17, 18, 20, 23, 24, 26, 29, 32, 33, 35, 38, 41, 42, 45, 46, 48, 51, 54, 55, 58, 59, 61, 64, 65, 67, 70, 73, 74, 77, 78, 80, 83, 84, 86, 89, 92, 93, 95, 98, 101, 102, 105, 106, 108, 111, 112, 114, 117, 120, 121, 123, 126, 129, 130, 133

Offset: 1

Reinhard Zumkeller, Dec 17 2011

nonn

Position of the n-th occurrence of the digit 1 in A105083(n-1) for n>=1. - Jeffrey Shallit, Mar 08 2025

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Larry Ericksen and Peter G. Anderson, Patterns in differences between rows in k-Zeckendorf arrays, The Fibonacci Quarterly, Vol. 50, No. 1 (February 2012), pp. 11-18.
Jeffrey Shallit, The Narayana Morphism and Related Words, arXiv:2503.01026 [math.CO], 2025.
Eric Weisstein's World of Mathematics, Hofstadter H-Sequence.
Wikipedia, Hofstadter sequence
Index entries for Hofstadter-type sequences

Cf. A005374, A105083, A202340, A136495, A136496, A202341 (complement).

import Data.List (elemIndices)
a202342 n = a202342_list !! (n-1)
a202342_list = elemIndices 2 a202340_list

A202340(a(n)) = 2.
a(n) = A005374(A136496(n)). - Alan Michael Gómez Calderón, Dec 22 2024
a(n) = A136495(A136495(n)). - Alan Michael Gómez Calderón, Jan 06 2025

A136495 Solution of the complementary equation b(n)=a(a(n))+n.

Original entry on oeis.org

1, 3, 4, 5, 7, 9, 10, 12, 13, 14, 16, 17, 18, 20, 22, 23, 24, 26, 28, 29, 31, 32, 33, 35, 37, 38, 40, 41, 42, 44, 45, 46, 48, 50, 51, 53, 54, 55, 57, 58, 59, 61, 63, 64, 65, 67, 69, 70, 72, 73, 74, 76, 77, 78, 80, 82, 83, 84, 86, 88, 89, 91, 92, 93, 95, 97, 98, 100, 101, 102

Offset: 1

Clark Kimberling, Jan 01 2008

nonn

b = 1 + (column 1 of Z) = 1 + A020942. The pair (a,b) also satisfy the following complementary equations: b(n)=a(a(a(n)))+1; a(b(n))=a(n)+b(n); b(a(n))=a(n)+b(n)-1; (and others).
Let Z = (3rd order Zeckendorf array) = A136189. Then a = ordered union of columns 1,3,4,6,7,9,10,12,13,... of Z, b = ordered union of columns 2,5,8,11,14,... of Z.
Position of the n-th occurrence of either 1 or 3 in A105083(n-1) for n>=1. - Jeffrey Shallit, Mar 08 2025

			b(1) = a(a(1))+1 = a(1)+1 = 1+1 = 2;
b(2) = a(a(2))+2 = a(3)+2 = 4+2 = 6;
b(3) = a(a(3))+3 = a(4)+3 = 5+3 = 8;
b(4) = a(a(4))+4 = a(5)+4 = 7+4 = 11.

Clark Kimberling and Peter J. C. Moses, Complementary equations and Zeckendorf arrays, in Applications of Fibonacci Numbers, vol.10, Proceedings of the Thirteenth International Conference on Fibonacci Numbers and Their Applications, William Webb, editor, Congressus Numerantium, Winnipeg, Manitoba 201 (2010) 161-178.

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Jeffrey Shallit, The Narayana Morphism and Related Words, arXiv:2503.01026 [math.CO], 2025.
Eric Weisstein's World of Mathematics, Hofstadter H-Sequence.

Cf. A005374, A020942, A035513, A105083, A136189, A136496.

import Data.List (elemIndex)
import Data.Maybe (fromJust)
a136495 n = (fromJust $ n `elemIndex` tail a005374_list) + 1
-- Reinhard Zumkeller, Dec 17 2011

A005374(a(n)) = n. - Reinhard Zumkeller, Dec 17 2011

a(n) = A005374(A005374(n-1)) + n. - Alan Michael Gómez Calderón, Jul 16 2025

A136496 Solution of the complementary equation b(n)=a(a(n))+n; this is sequence b; sequence a is A136495.

Original entry on oeis.org

2, 6, 8, 11, 15, 19, 21, 25, 27, 30, 34, 36, 39, 43, 47, 49, 52, 56, 60, 62, 66, 68, 71, 75, 79, 81, 85, 87, 90, 94, 96, 99, 103, 107, 109, 113, 115, 118, 122, 124, 127, 131, 135, 137, 140, 144, 148, 150, 154, 156, 159, 163, 165, 168, 172, 176, 178, 181, 185, 189

Offset: 1

Clark Kimberling, Jan 01 2008

nonn

b = 1 + (column 1 of Z) = 1 + A020942. The pair (a,b) also satisfy the following complementary equations: b(n)=a(a(a(n)))+1; a(b(n))=a(n)+b(n); b(a(n))=a(n)+b(n)-1; (and others).

Position of the n-th occurrence of the digit 2 in A105083(n-1) for n>=1. - Jeffrey Shallit, Mar 08 2025

			b(1) = a(a(1))+1 = a(1)+1 = 1+1 = 2;
b(2) = a(a(2))+2 = a(3)+2 = 4+2 = 6;
b(3) = a(a(3))+3 = a(4)+3 = 5+3 = 8;
b(4) = a(a(4))+4 = a(5)+4 = 7+4 = 11.

Clark Kimberling and Peter J. C. Moses, Complementary equations and Zeckendorf arrays, in Applications of Fibonacci Numbers, vol.10, Proceedings of the Thirteenth International Conference on Fibonacci Numbers and Their Applications, William Webb, editor, Congressus Numerantium, Winnipeg, Manitoba 201 (2010) 161-178.

Jeffrey Shallit, The Narayana Morphism and Related Words, arXiv:2503.01026 [math.CO], 2025.

Cf. A020942, A035513, A105083, A136189, A136495.

Let Z = (3rd order Zeckendorf array) = A136189. Then a = ordered union of columns 1,3,4,6,7,9,10,12,13,... of Z, b = ordered union of columns 2,5,8,11,14,... of Z.

a(n) = A136495(n) + A005374(n-1) + n. - Alan Michael Gómez Calderón, Dec 23 2024

A245553 A Rauzy fractal sequence: trajectory of 1 under morphism 1 -> 2,3; 2 -> 3; 3 -> 1.

Original entry on oeis.org

1, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 1, 2, 3, 2, 3, 3, 1, 3, 1, 1, 2, 3, 3, 1, 1, 2, 3, 1, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 1, 2, 3, 3, 1, 1, 2, 3, 1, 2, 3, 2, 3, 3, 1, 3, 1, 1, 2, 3, 1, 2, 3, 2, 3, 3, 1, 1, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 1, 2, 3

Offset: 1

N. J. A. Sloane, Aug 03 2014

nonn

P. Arnoux and E. Harriss, What is a Rauzy Fractal?, Notices Amer. Math. Soc., 61 (No. 7, 2014), 768-770, also p. 704 and front cover.
Marcy Barge and Jaroslaw Kwapisz, Geometric theory of unimodular Pisot substitutions, Amer. J. Math. 128 (2006), no. 5, 1219--1282. MR2262174 (2007m:37039). See Fig. 18.1.
Index entries for sequences that are fixed points of mappings

Cf. A092782, A245554, A105083.

Nest[ Function[ l, {Flatten[(l /. {1 -> {2, 3}, 2 -> {3}, 3 -> {1}})] }], {1}, 15]

A245554 A Rauzy fractal sequence: trajectory of 1 under morphism 1 -> 1,2,1,3; 2 -> 3; 3 -> 1.

Original entry on oeis.org

1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 2, 1, 3, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 2, 1, 3, 3, 1, 2, 1, 3, 1, 1, 1, 2, 1, 3, 3, 1, 2

Offset: 1

N. J. A. Sloane, Aug 03 2014

nonn

P. Arnoux and E. Harriss, What is a Rauzy Fractal?, Notices Amer. Math. Soc., 61 (No. 7, 2014), 768-770, also p. 704 and front cover.
Marcy Barge and Jaroslaw Kwapisz, Geometric theory of unimodular Pisot substitutions, Amer. J. Math. 128 (2006), no. 5, 1219--1282. MR2262174 (2007m:37039). See Fig. 18.1.
Index entries for sequences that are fixed points of mappings

Cf. A092782, A245553, A105083.

Nest[ Function[ l, {Flatten[(l /. {1 -> {1, 2, 1, 3}, 2 -> {3}, 3 -> {1}})] }], {1}, 9]

A245555 Trajectory of 1 under the morphism 1 -> 12, 2 -> 23, 3 -> 31.

Original entry on oeis.org

1, 2, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 1, 2, 2, 3, 3, 1, 3, 1, 1, 2, 3, 1, 1, 2, 1, 2, 2, 3, 2, 3, 3, 1, 3, 1, 1, 2, 3, 1, 1, 2, 1, 2, 2, 3, 3, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 1, 2, 3, 1, 1, 2, 1, 2, 2, 3, 3, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3

Offset: 1

N. J. A. Sloane, Aug 03 2014

nonn

The morphism 1->12, 2->21 gives the {1,2} version of the Thue-Morse sequence A001285, cf. A010060.

The morphism 0->01, 1->12, 2->20 gives the generalized Thue-Morse sequence A071858.

Cf. A001285, A010060, A092782, A105083, A245553, A245554.

Essentially the same as A071858.

Nest[ Function[ l, {Flatten[(l /. {1 -> {1, 2}, 2 -> {2, 3}, 3 -> {3, 1}})] }], {1}, 9]

{a(n) = my(v = [1]); if( n<1, 0, while( #vMichael Somos, Aug 05 2014 */

a(n) = A071858(n+1) + 1. - Michel Dekking, Sep 29 2020

cp's OEIS Frontend

A381841 Position of the n-th occurrence of the digit 3 in A105083(n-1) for n>=1.

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A092782 The ternary tribonacci word; also a Rauzy fractal sequence: fixed point of the morphism 1 -> 12, 2 -> 13, 3 -> 1, starting from a(1) = 1.

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A073058 Define s(1)={1,2}, s(2)={1,3} and s(3)={1}. For a finite sequence A={a_1, ..., a_n}, with elements in {1,2,3}, define t(A) to be the concatenation of A, s(a_1), s(a_2), ... and s(a_n). Start with the sequence {1,2,3} and repeatedly apply t; limiting sequence is shown.

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A202342 Numbers occurring exactly twice in Hofstadter H-sequence A005374.

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A136495 Solution of the complementary equation b(n)=a(a(n))+n.

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A136496 Solution of the complementary equation b(n)=a(a(n))+n; this is sequence b; sequence a is A136495.

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A245553 A Rauzy fractal sequence: trajectory of 1 under morphism 1 -> 2,3; 2 -> 3; 3 -> 1.

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A245554 A Rauzy fractal sequence: trajectory of 1 under morphism 1 -> 1,2,1,3; 2 -> 3; 3 -> 1.

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