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 A071656 #5 Apr 30 2014 01:53:47 %S A071656 0,1,3,2,7,6,8,4,5,17,16,18,14,15,20,19,22,9,10,21,11,12,13,45,44,46, %T A071656 42,43,48,47,50,37,38,49,39,40,41,54,53,55,51,52,61,60,63,23,24,62,25, %U A071656 26,27,57,56,64,28,29,58,30,31,32,59,33,34,35,36,129,128,130,126,127 %N A071656 Permutation of natural numbers induced by the automorphism car_cdr_robl! acting on the parenthesizations encoded by A014486. %H A071656 A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (Includes the complete Scheme source for computing this sequence) %H A071656 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A071656 (Scheme function implementing this automorphism on list-structures:) %o A071656 (define (car_cdr_robl! s) (cond ((not (pair? s))) ((not (pair? (cdr s))) (swap! s)) (else (car_cdr_robl! (car s)) (car_cdr_robl! (cdr s)) (robl! s))) s) %o A071656 (define (robl! s) (let ((ex-car (car s))) (set-car! s (cddr s)) (set-cdr! (cdr s) ex-car) (swap! (cdr s)) (swap! s) s)) %o A071656 (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s)) %Y A071656 Inverse permutation: A071655. The car/cdr-flipped conjugate of A071659, i.e. A071656(n) = A057163(A071659(A057163(n))). Cf. also A071657, A071658. %K A071656 nonn %O A071656 0,3 %A A071656 _Antti Karttunen_, May 30 2002