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 A071658 #5 Apr 30 2014 01:53:47 %S A071658 0,1,3,2,8,6,7,4,5,20,19,22,14,15,21,16,17,9,10,18,11,12,13,64,53,55, %T A071658 51,52,54,60,62,37,38,61,39,40,41,57,56,63,42,43,58,44,45,23,24,46,25, %U A071658 26,27,59,47,48,28,29,49,30,31,32,50,33,34,35,36,162,191,192,154,155 %N A071658 Permutation of natural numbers induced by the automorphism cdr_robl_car! acting on the parenthesizations encoded by A014486. %H A071658 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 A071658 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A071658 (Scheme function implementing this automorphism on list-structures:) %o A071658 (define (cdr_robl_car! s) (cond ((not (pair? s))) ((not (pair? (cdr s))) (swap! s)) (else (cdr_robl_car! (cdr s)) (robl! s) (cdr_robl_car! (car s)))) s) %o A071658 (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 A071658 (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s)) %Y A071658 Inverse permutation: A071657 and also its car/cdr-flipped conjugate, i.e. A071658(n) = A057163(A071657(A057163(n))). Cf. also A071655, A071656, A071659, A071660. %K A071658 nonn %O A071658 0,3 %A A071658 _Antti Karttunen_, May 30 2002