This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A072094 #5 May 01 2014 02:47:41 %S A072094 0,1,3,2,7,8,5,4,6,17,18,20,21,22,13,12,10,9,11,15,14,16,19,45,46,48, %T A072094 49,50,54,55,57,58,59,61,62,63,64,35,36,32,31,34,26,27,24,23,25,29,28, %U A072094 30,33,41,40,38,37,39,43,42,44,47,52,51,53,56,60,129,130,132,133,134 %N A072094 Permutation of natural numbers induced by the automorphism cdr_robr_cdr! acting on the parenthesizations encoded by A014486. %H A072094 A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (Includes the complete Scheme program for computing this sequence) %H A072094 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A072094 (Scheme function implementing this automorphism on list-structures:) %o A072094 (define (cdr_robr_cdr! s) (cond ((not (pair? s))) ((not (pair? (car s))) (swap! s)) (else (cdr_robr_cdr! (cdr s)) (robr! s) (cdr_robr_cdr! (cdr s)))) s) %o A072094 (define (robr! s) (let ((ex-cdr (cdr s))) (set-cdr! s (caar s)) (set-car! (car s) ex-cdr) (swap! (car s)) (swap! s) s)) %o A072094 (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s)) %Y A072094 Inverse permutation: A072095. The car/cdr-flipped conjugate of A072093, i.e. A072094(n) = A057163(A072093(A057163(n))). Cf. also A071655-A071660, A072090-A072091. %K A072094 nonn %O A072094 0,3 %A A072094 _Antti Karttunen_, Jun 25 2002