cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 10 results.

A103269 Apply the tribonacci morphism 1 -> {1, 2}, 2 -> {1, 3}, 3 -> {1} n times to 1, and concatenate the resulting string.

Original entry on oeis.org

1, 12, 1213, 1213121, 1213121121312, 121312112131212131211213, 12131211213121213121121312131211213121213121, 121312112131212131211213121312112131212131211213121121312121312112131213121121312
Offset: 0

Views

Author

Keywords

Comments

The number of letters in the n-th iteration is tribonacci(n+3) (that is, A000073(n+3)).

Crossrefs

A092782 is limit of these strings.

Programs

  • Mathematica
    FromDigits /@ NestList[ Flatten[ # /. {1 -> {1, 2}, 2 -> {1, 3}, 3 -> 1}] &, {1}, 7]
    (* Second program: *)
    FromDigits /@ SubstitutionSystem[{1 -> {1, 2}, 2 -> {1, 3}, 3 -> {1}}, {1}, 7] (* Jean-François Alcover, Nov 12 2018 *)

Extensions

Definition edited by N. J. A. Sloane, Aug 06 2018

A106748 Define the morphism f: 1->113, 2->13, 3->2 and let a(0) = 1; then a(n+1) = f(a(n)).

Original entry on oeis.org

1, 113, 1131132, 1131132113113213, 113113211311321311311321131132131132, 113113211311321311311321131132131132113113211311321311311321131132131132113113213
Offset: 0

Views

Author

N. J. A. Sloane, May 16 2005

Keywords

References

  • E. Bombieri and J. Taylor, Which distribution of matter diffracts? An initial investigation, in International Workshop on Aperiodic Crystals (Les Houches, 1986), J. de Physique, Colloq. C3, 47 (1986), C3-19 to C3-28.

Crossrefs

Cf. A106749.

Programs

  • Mathematica
    FromDigits /@ NestList[ Flatten[ # /. {1 -> {1, 1, 3}, 2 -> {1, 3}, 3 -> 2}] &, {1}, 5] (* Robert G. Wilson v, May 17 2005 *)

Extensions

More terms from Robert G. Wilson v, May 17 2005

A106750 Define the "Fibonacci" morphism f: 1->12, 2->1 and let a(0) = 2; then a(n+1) = f(a(n)).

Original entry on oeis.org

2, 1, 12, 121, 12112, 12112121, 1211212112112, 121121211211212112121, 1211212112112121121211211212112112, 1211212112112121121211211212112112121121211211212112121
Offset: 0

Views

Author

N. J. A. Sloane, May 16 2005. Initial term 2 added by N. J. A. Sloane, Jul 05 2012

Keywords

Comments

a(n) converges to the Fibonacci word A003842.
a(n) has length Fibonacci(n+1) (cf. A000045).

References

  • Berstel, Jean. "Fibonacci words—a survey." In The book of L, pp. 13-27. Springer Berlin Heidelberg, 1986.
  • E. Bombieri and J. Taylor, Which distribution of matter diffracts? An initial investigation, in International Workshop on Aperiodic Crystals (Les Houches, 1986), J. de Physique, Colloq. C3, 47 (1986), C3-19 to C3-28.

Crossrefs

Programs

  • Mathematica
    FromDigits /@ NestList[ Flatten[ # /. {1 -> {1, 2}, 2 -> 1}] &, {2}, 8] (* Robert G. Wilson v, May 17 2005 *)

Extensions

More terms from Robert G. Wilson v, May 17 2005

A106795 Fixed point of the morphism 1 -> 1,1,1,1,1,1,2,2,2,3; 2 -> 2,2,3,1,1,1,1; 3 -> 3,1,1,1,2,2, starting with a(0) = 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 3, 1, 1, 1, 2, 2
Offset: 0

Views

Author

Roger L. Bagula, May 17 2005

Keywords

Comments

3-symbol substitution for the characteristic polynomial: x^3 + 9*x^2 - 3*x - 1.

Examples

			The first few steps of the substitution are:
Start: 1
Maps:
  1 --> 1 1 1 1 1 1 2 2 2 3
  2 --> 2 2 3 1 1 1 1
  3 --> 3 1 1 1 2 2
-------------
0:   (#=1)
  1
1:   (#=10)
  1111112223
		

Crossrefs

Programs

  • Mathematica
    s[1]= {1,1,1,1,1,1,2,2,2,3}; s[2]= {2,2,3,1,1,1,1}; s[3]= {3,1,1,1,2,2};
    t[a_]:= Flatten[s /@ a]; p[0]= {1}; p[1]= t[p[0]]; p[n_]:= t[p[n-1]]; p[3]

Extensions

Edited by G. C. Greubel, Apr 03 2022

A106796 Fixed point of the morphism 1 -> 1,1,2; 2 -> 3; 3 -> 1,4; 4 -> 1, starting with a(0) = 1.

Original entry on oeis.org

1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 1, 2, 3
Offset: 0

Views

Author

Roger L. Bagula, May 17 2005

Keywords

Comments

4-symbol substitution for the Pisot characteristic polynomial: x^4 - 2*x^2 - x - 1.

Examples

			The first few steps of the substitution are:
Start: 1
Maps:
  1 --> 1 1 2
  2 --> 3
  3 --> 1 4
  4 --> 1
-------------
0:   (#=1)
  1
1:   (#=3)
  112
2:   (#=7)
  1121123
3:   (#=16)
  1121123112112314
4:   (#=36)
  112112311211231411211231121123141121
5:   (#=82)
  1121123112112314112112311211231411211121123112112314112112311211231411211121123112
		

Crossrefs

Programs

  • Mathematica
    s[1]= {1, 1, 2}; s[2]= {3}; s[3]= {1, 4}; s[4]= {1}; t[b_]:= Flatten[s /@ b];
    a[0]= {1}; a[1]= t[p[0]]; a[n_]:= t[a[n-1]];
    a[10]

Extensions

Edited by G. C. Greubel, Apr 03 2022

A106797 Fixed point of the morphism 1 -> 1,1,1,1,2,2,3; 2 -> 4,1; 3 -> 2,1,1,1; 4 -> 1,2,1 starting with a(0) = 1.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 4, 1, 4, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 4, 1, 4, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 2, 2, 3, 4, 1, 4, 1, 2
Offset: 0

Views

Author

Roger L. Bagula, May 17 2005

Keywords

Comments

4-symbol substitution of the Pisot characteristic polynomial: x^4 - 4*x^3 - 6*x^2 - x - 1.

Examples

			The first few steps of the substitution are:
Start: 1
Maps:
  1 --> 1 1 1 1 2 2 3
  2 --> 4 1
  3 --> 2 1 1 1
  4 --> 1 2 1
-------------
0:   (#=1)
  1
1:   (#=7)
  1111223
2:   (#=36)
  111122311112231111223111122341412111
		

Crossrefs

Programs

  • Mathematica
    s[1]= {1,1,1,1,2,2,3}; s[2]= {4,1}; s[3]= {2,1,1,1}; s[4]= {1,2,1};
    t[a_]:= Flatten[s /@ a]; p[0]= {1}; p[1]= t[p[0]]; p[n_]:= t[p[n-1]]; p[3]

Extensions

Edited by G. C. Greubel, Apr 03 2022

A106798 Fixed point of the morphism 1 -> 3; 2 -> 1,2,2; 3 -> 1,2, starting with a(0) = 1.

Original entry on oeis.org

1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 2, 3, 1, 2, 2, 1, 2, 2, 3, 1
Offset: 0

Views

Author

Roger L. Bagula, May 17 2005

Keywords

Comments

3-symbol substitution for the characteristic polynomial: x^3 - 2*x^2 - x + 1.

Examples

			The first few steps of the substitution are:
Start: 1
Maps:
  1 --> 3
  2 --> 1 2 2
  3 --> 1 2
-------------
a(n) = p(2*n)
-------------
0:   (#=1) (p(0))
  1
1:   (#=2) (p(2))
  12
2:   (#=9) (p(4))
  123122122
3:   (#=45) (p(6))
  123122122312212312212231221221231221223122122
		

Crossrefs

Programs

  • Mathematica
    s[1]= {3}; s[2]= {1,2,2}; s[3]= {1,2}; t[b_]:= Flatten[s /@ b];
    p[0]= {1}; p[1]= t[p[0]]; p[n_]:= t[p[n-1]];
    a[n_]:= p[2*n];
    a[4]

Formula

a(n) = p(2*n), where p(n) maps the fixed point morphism 1 -> 3; 2 -> 1,2,2; 3 -> 1,2, starting with p(0) = 1.

Extensions

Edited by G. C. Greubel, Apr 03 2022

A107292 3-symbol substitution with characteristic real root polynomial:m x^3-2*x^2-2*x+2.

Original entry on oeis.org

1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 3, 1, 3, 3, 1, 3, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 2, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 2, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 3, 1, 3, 3, 1, 3, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 3, 1, 3, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 3, 1, 3, 3, 1, 3, 1, 3, 3, 1, 2, 2, 1, 3, 3, 1, 3, 1, 3, 1, 3, 3, 1, 2, 2, 1, 3, 3
Offset: 0

Views

Author

Roger L. Bagula, May 20 2005

Keywords

Comments

This is a real root cubic:{{x -> -1.17009}, {x -> 0.688892}, {x -> 2.48119}} like the Bombieri aperiodic: a Bombieri silver Isomer substitution: ( same characteristic polynomial) 1->{3},2->{2,1,2},3->{1,2,2,1}

Crossrefs

Programs

  • Mathematica
    s[1] = {1, 3, 3, 1}; s[2] = {3, 1, 3}; s[3] = {2}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]] aa = p[5]

Formula

1->{1, 3, 3, 1}, 2->{3, 1, 3}, 3->{2}

A107296 Three-symbol substitution with real Pisot characteristic polynomial: x^3-3*x^2-x-2.

Original entry on oeis.org

1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 3, 1
Offset: 0

Views

Author

Roger L. Bagula, May 20 2005

Keywords

Comments

Bombieri type Real Roots: {{x -> -0.860806}, {x -> 0.745898}, {x -> 3.11491}} Matrix isomer: 1->{3},{2->{2,1,2,2},3->{1,2} I found this while trying to get a substitution for the Frougny real root characteristic polynomial: x^3-3*x^2+1

Crossrefs

Programs

  • Mathematica
    s[1] = {1, 3, 1, 1}; s[2] = {1, 3}; s[3] = {2}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]] aa = p[4]

Formula

1->{1, 3, 1, 1}, 2->{1, 3}, 2->{2}

A107297 Limit of the string substitution 1->{1, 3, 1, 1}, 2->{1}, 3->{2}.

Original entry on oeis.org

1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 2, 1, 3
Offset: 1

Views

Author

Roger L. Bagula, May 20 2005

Keywords

Crossrefs

Programs

  • Mathematica
    s[1] = {1, 3, 1, 1}; s[2] = {1}; s[3] = {2};
    t[a_] := Flatten[s /@ a];
    p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]]
    aa = p[5]

Extensions

Edited by and meaningful name from Joerg Arndt, Jun 30 2023
Showing 1-10 of 10 results.