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 A225589 #18 May 11 2013 14:49:12 %S A225589 1,2,4,3,8,5,6,16,7,9,10,12,11,32,13,14,17,15,18,20,19,24,21,22,64,23, %T A225589 25,26,28,27,33,29,30,34,31,36,35,40,37,38,48,39,41,42,44,43,128,45, %U A225589 46,49,47,50,52,51,56,53,54,65,55,57,58,60,59,66,61,62,68 %N A225589 Inverse of permutation in A217122. %H A225589 Reinhard Zumkeller, <a href="/A225589/b225589.txt">Table of n, a(n) for n = 1..10000</a> %H A225589 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A225589 (Haskell) %o A225589 import Data.List (elemIndex) %o A225589 import Data.Maybe (fromJust) %o A225589 a225589 = (+ 1) . fromJust . (`elemIndex` a217122_list) %K A225589 nonn %O A225589 1,2 %A A225589 _Reinhard Zumkeller_, May 11 2013