0,3

SPINE-transformation is explained in A122203. This automorphism permutes the top-level of a list of even length (1 ... 2n) as (2n 1 2n-1 2 2n-3 3 ... n+1 n) and when applied to a list of odd length (1 .. 2n+1), permutes it as (2n+1 1 2n 2 2n-1 3 ... n n+1). Used to construct A127287 and A127289.

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 (*A127285! s) (cond ((pair? s) (*A057508! s) (*A127285! (cdr s)))) s)

Inverse: A127286. a(n) = A127287(A057508(n)).

Sequence in context: A129606 A057510 A130920 this_sequence A130945 A073285 A057512

Adjacent sequences: A127282 A127283 A127284 this_sequence A127286 A127287 A127288

nonn

Antti Karttunen (His-Firstname.His-Surname(AT)gmail.com), Jan 16 2007