0,3

This automorphism permutes the top-level of a list of even length (1 ... 2n) as (1 2n 2 2n-1 3 2n-3 ... n n+1) and when applied to a list of odd length (1 .. 2n+1), permutes it as (1 2n+1 2 2n 3 2n-1 ... n n+1). Used to construct A127291.

A. Karttunen, Table of n, a(n) for n = 0..2055

Index entries for signature-permutations of Catalan automorphisms

(Scheme implementation of this automorphism, destructive, that acts on S-expressions, i.e. list-structures:)

(define (*A127287! s) (*A127285! (*A057508! s)))

Inverse: A127288. a(n) = A127285(A057508(n)).

Sequence in context: A261333 A031086 A127288 * A239088 A162344 A283962

Adjacent sequences: A127284 A127285 A127286 * A127288 A127289 A127290

nonn

Antti Karttunen, Jan 16 2007

approved