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 A261351 #7 Mar 22 2022 00:11:51 %S A261351 1,2,4,3,6,8,5,9,7,12,10,13,11,16,14,17,15,20,18,21,19,24,22,25,23,28, %T A261351 26,29,27,32,30,33,31,36,34,37,35,40,38,41,39,44,42,45,43,48,46,49,47, %U A261351 52,50,53,51,56,54,57,55,60,58,61,59,64,62,65,63,68,66 %N A261351 Inverse permutation to A084385. %C A261351 -4 <= a(n) - A084385(n) <= 3; %C A261351 for n > 4: a(n) != A084385(n); %C A261351 for n > 7: a(n) >= A084385(n) - 3. %H A261351 Reinhard Zumkeller, <a href="/A261351/b261351.txt">Table of n, a(n) for n = 1..10000</a> %H A261351 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A261351 (Haskell) %o A261351 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A261351 a261351 = (+ 1) . fromJust . (`elemIndex` a084385_list) %Y A261351 Cf. A084385. %K A261351 nonn %O A261351 1,2 %A A261351 _Reinhard Zumkeller_, Aug 16 2015