A135352 Period 5: repeat [1,2,2,1,3].

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

Offset

1,2

Comments

This sequence (if extended to be bi-infinite) is the quiddity sequence of the unique width-5 Coxeter frieze pattern A139434; equivalently, if one goes around the (uniquely) triangulated regular pentagon and sequentially looks at its vertices, counting the number of triangles incident with each vertex, then this sequence will be obtained. - Andrey Zabolotskiy, May 04 2023

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Karin Baur, Frieze Patterns of Integers, Math. Intelligencer 43, 47-54 (2021). See Example 2 and Figure 4.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,1).

Mathematica

PadRight[{}, 120, {1, 2, 2, 1, 3}] (* Harvey P. Dale, Dec 12 2025 *)

Crossrefs

Cf. A076839, A139434.

Sequence in context: A283196 A238882 A279287 * A320040 A072528 A368060

Adjacent sequences: A135349 A135350 A135351 * A135353 A135354 A135355

Keyword

nonn,easy

Author

Roger L. Bagula, Feb 16 2008

Extensions

Edited by Joerg Arndt, Oct 11 2016

Initial term 1 removed by Joerg Arndt, May 04 2023

Status

approved