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 A143053 #5 Mar 30 2012 18:51:00 %S A143053 0,1,3,4,2,8,9,5,6,7,15,16,10,11,12,13,14,24,25,17,18,19,20,21,22,23, %T A143053 35,36,26,27,28,29,30,31,32,33,34,48,49,37,38,39,40,41,42,43,44,45,46, %U A143053 47,63,64,50,51,52,53,54,55,56,57,58,59,60,61,62,80,81,65,66,67,68,69,70 %N A143053 A143051(A143051(n)). %C A143053 Permutation of the natural numbers, inverse: A143054; %C A143053 a(A000290(n)) = A008865(n) for n>1; %C A143053 a(A002522(n)) = A000290(n+1) for n>0. %H A143053 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A143053 nonn %O A143053 0,3 %A A143053 _Reinhard Zumkeller_, Jul 20 2008