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 A252448 #5 Dec 17 2014 20:52:28 %S A252448 2,1,4,5,7,3,9,8,11,12,18,6,13,14,16,10,20,17,24,25,31,15,26,19,22,23, %T A252448 33,32,39,27,29,21,35,34,37,40,50,30,41,42,48,38,52,49,60,61,71,28,43, %U A252448 44,46,36,54,47,62,63,69,45,64,51,58,59,73,72,83,53,56 %N A252448 Inverse permutation to A249990. %H A252448 Reinhard Zumkeller, <a href="/A252448/b252448.txt">Table of n, a(n) for n = 1..10000</a> %H A252448 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A252448 (Haskell) %o A252448 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A252448 a252448 = (+ 1) . fromJust . (`elemIndex` a249990_list) %Y A252448 Cf. A249990 (inverse), A252458 (fixed points). %K A252448 nonn %O A252448 1,1 %A A252448 _Reinhard Zumkeller_, Dec 17 2014