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 A143054 #5 Mar 30 2012 18:51:00 %S A143054 0,1,4,2,3,7,8,9,5,6,12,13,14,15,16,10,11,19,20,21,22,23,24,25,17,18, %T A143054 28,29,30,31,32,33,34,35,36,26,27,39,40,41,42,43,44,45,46,47,48,49,37, %U A143054 38,52,53,54,55,56,57,58,59,60,61,62,63,64,50,51,67,68,69,70,71,72,73,74 %N A143054 A143052(A143052(n)). %C A143054 Permutation of the natural numbers, inverse: A143053; %C A143054 For n>1: a(A008865(n))=A000290(n), %C A143054 a(A000290(n))=A000290(n)-A005408(n-2). %H A143054 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A143054 nonn %O A143054 0,3 %A A143054 _Reinhard Zumkeller_, Jul 20 2008