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 A257677 #7 May 05 2015 13:58:49 %S A257677 0,1,2,3,5,4,6,7,9,8,10,13,11,12,14,15,17,16,18,21,19,20,22,27,23,24, %T A257677 29,28,25,26,30,31,33,32,34,37,35,36,38,43,39,40,45,44,41,42,53,46,54, %U A257677 55,47,52,56,57,48,51,58,61,49,50,59,60,62,63,65,64,66,69,67,68,70,75,71,72,77,76,73,74,85,78,86,87,79 %N A257677 Inverse permutation to A257676. %H A257677 Antti Karttunen, <a href="/A257677/b257677.txt">Table of n, a(n) for n = 0..8191</a> %H A257677 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A257677 (Scheme, requiring also defineperm1-macro from _Antti Karttunen_'s IntSeq-library) %o A257677 ;; When A257676 is defined with defineperm1-macro, it will automatically cache also the inverse values, which are then available with negative arguments: %o A257677 (define (A257677 n) (A257676 (- n))) %Y A257677 Inverse: A257676. %Y A257677 Fixed points: A257678. %K A257677 nonn %O A257677 0,3 %A A257677 _Antti Karttunen_, May 04 2015