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

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

1,8

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.

Links

Clark Kimberling, Table of n, a(n) for n = 1..10000 [a(9842) corrected by Zhuorui He, Sep 04 2025]

Example

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

Mathematica

Nest[Flatten[# /. {0 -> {1, 2, 0}, 1 -> {1, 1, 0}, 2 -> {1, 0, 0}}] &, {0}, 9];

Prog

(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

Crossrefs

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

Sequence in context: A164067 A353918 A387790 * A374060 A375149 A392629

Adjacent sequences: A305487 A305488 A305489 * A305491 A305492 A305493

Keyword

nonn,easy

Author

Clark Kimberling, Jun 02 2018

Status

approved