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 A249571 #7 Mar 22 2022 00:11:07 %S A249571 1,2,4,3,7,5,11,6,8,9,12,10,14,13,15,16,17,20,18,21,24,25,19,26,28,29, %T A249571 31,33,22,35,23,36,39,40,43,44,27,46,48,49,30,52,32,56,57,59,34,60,62, %U A249571 63,66,67,37,69,70,73,76,77,38,79,41,82,83,85,86,88,42 %N A249571 Inverse permutation to A249054. %H A249571 Reinhard Zumkeller, <a href="/A249571/b249571.txt">Table of n, a(n) for n = 1..10000</a> %H A249571 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A249571 (Haskell) %o A249571 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A249571 a249571 = (+ 1) . fromJust . (`elemIndex` a249054_list) %Y A249571 Cf. A249054. %K A249571 nonn %O A249571 1,2 %A A249571 _Reinhard Zumkeller_, Nov 01 2014