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 1-6 of 6 results.

A106749 Define the morphism f: 1->113, 2->13, 3->2; sequence gives trajectory of 1 under f.

Original entry on oeis.org

1, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 1, 1, 3, 2, 1, 1, 3, 1, 1, 3, 2, 1, 3, 1, 1, 3, 1, 1, 3, 2, 1
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. A106748.

Programs

  • Mathematica
    Nest[ Flatten[ # /. {1 -> {1, 1, 3}, 2 -> {1, 3}, 3 -> 2}] &, {1}, 6] (* Robert G. Wilson v, May 17 2005 *)

Extensions

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

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

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

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 1-6 of 6 results.