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 1-2 of 2 results.

A305490 Fixed point of the morphism 0->120, 1->110, 2->100.

Original entry on oeis.org

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

Views

Author

Clark Kimberling, Jun 02 2018

Keywords

Comments

This sequence is used to generate the anti-tribonacci sequence, A265389. The positions of 1 are also the positions of 0 in Stewart's choral sequence, A116178.

Examples

			1 -> 110 -> 110110120 -> ...
		

Crossrefs

Cf. A265389, A116178, A305495 (positions of 0), A189636 (positions of 1), A305496 (positions of 2).

Programs

  • Mathematica
    Nest[Flatten[# /. {0 -> {1, 2, 0}, 1 -> {1, 1, 0}, 2 -> {1, 0, 0}}] &, {0}, 9];
  • PARI
    A305490(n) = {n--;while(n%9==4,n=n\9);[1,1,0,1,1,0,1,2,0][n%9+1]}; \\ Zhuorui He, Sep 04 2025

A305496 Positions of 2 in the fixed point of the morphism 0->120, 1->110, 2->100 applied to 1 (as in A305490).

Original entry on oeis.org

8, 17, 26, 35, 44, 53, 62, 68, 71, 80, 89, 98, 107, 116, 125, 134, 143, 149, 152, 161, 170, 179, 188, 197, 206, 215, 224, 230, 233, 242, 251, 260, 269, 278, 287, 296, 305, 311, 314, 323, 332, 341, 350, 359, 368, 377, 386, 392, 395, 404, 413, 422, 431, 440
Offset: 1

Views

Author

Clark Kimberling, Jun 02 2018

Keywords

Comments

Let u, v, w be the position sequences of 0,1,2 in A305490. They partition the positive integers, and v is also the position sequence of 0 in Stewart's choral sequence, A116178.

Examples

			Fixed point: (1, 1, 0, 1, 1, 0, 1, 2, 0, 1, 1, 0, 1, 1, 0, 1, 2, 0, 1, 1, ... )
Positions of 0:  (3,6,9,12,15,18,21,23,  ... ) = A305495
Positions of 1:  (1,2,4,5,7,10,11,13,14, ... ) = A189636
Positions of 2:  (8,17,26,35,44,53,62,68,  ... ) = A305496
		

Crossrefs

Programs

  • Mathematica
    z = 120;
    t = Nest[Flatten[# /. {0 -> {1, 2, 0}, 1 -> {1, 1, 0},
          2 -> {1, 0, 0}}] &, {0}, 9]; (* A305490 *)
    Take[Flatten[Position[t, 0]], z] (* A305495  *)
    Take[Flatten[Position[t, 1]], z] (* A116178 *)
    Take[Flatten[Position[t, 2]], z] (* A305496 *)
    Position[SubstitutionSystem[{0->{1,2,0},1->{1,1,0},2->{1,0,0}},{1},{6}][[1]],2]//Flatten (* Harvey P. Dale, May 03 2022 *)
Showing 1-2 of 2 results.