A271491 Arises in enumeration of locally convex functions.

1, 3, 9, 16, 20, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21

Offset

0,2

Comments

All subsequent terms are 21.

See Coscia-DeWitt (2016) for precise definition.

Links

Table of n, a(n) for n=0..65.

Christopher Coscia and Jonathan DeWitt, Locally Convex Words and Permutations, Electronic Journal of Combinatorics. 23 (2), 2016, #P2.10.

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

Formula

a(n) = 21 for n >= 5.

Mathematica

PadRight[{1, 3, 9, 16, 20}, 100, 21] (* Paolo Xausa, Feb 03 2026 *)

Crossrefs

Cf. A271492, A271493.

Sequence in context: A366051 A070066 A299636 * A359618 A214644 A184529

Adjacent sequences: A271488 A271489 A271490 * A271492 A271493 A271494

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 15 2016

Status

approved