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 A247879 #26 Feb 23 2015 10:51:48 %S A247879 1,4,7,10,13,16,19,22,25,2,3,28,37,40,55,64,67,82,91,5,6,33,43,53,57, %T A247879 70,77,90,94,8,9,29,46,51,59,73,81,89,97,11,12,34,38,49,61,66,76,88, %U A247879 100,14,15,30,41,44,63,69,80,87,103,17,18,35,47,54,56,72 %N A247879 Inverse permutation to A248025. %H A247879 Reinhard Zumkeller, <a href="/A247879/b247879.txt">Table of n, a(n) for n = 1..10000</a> %H A247879 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A247879 (Haskell) %o A247879 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A247879 a247879 = (+ 1) . fromJust . (`elemIndex` a248025_list) %K A247879 nonn %O A247879 1,2 %A A247879 _Reinhard Zumkeller_, Sep 30 2014