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 A167905 #4 Mar 30 2012 18:51:05 %S A167905 1,2,3,4,6,5,8,7,10,9,12,11,16,14,13,15,17,18,19,20,21,22,24,23,26,27, %T A167905 28,25,30,29,34,31,32,33,35,36,37,39,40,38,43,42,41,44,45,46,47,48,49, %U A167905 51,52,50,54,53,56,55,58,57,62,61,59,60,63,64,65,66,67,69,70,68,72,71 %N A167905 Inverse integer permutation to A121878. %C A167905 a(A167906(n)) = A167906(n); %C A167905 a(A121878(n)) = A121878(a(n)) = n; %C A167905 a(A167904(n)) = A167904(a(n)) = A121878(n). %H A167905 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A167905 nonn %O A167905 1,2 %A A167905 _Reinhard Zumkeller_, Nov 15 2009