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 A194919 #5 Mar 30 2012 18:57:44 %S A194919 1,3,2,5,6,4,8,10,9,7,12,15,14,13,11,17,20,21,19,18,16,23,26,28,27,25, %T A194919 24,22,30,33,35,36,34,32,31,29,38,41,43,45,44,42,40,39,37,47,50,52,55, %U A194919 54,53,51,49,48,46,57,60,62,65,66,64,63,61,59,58,56,68,71,73 %N A194919 Inverse permutation of A194918; every positive integer occurs exactly once. %t A194919 (See A194918.) %Y A194919 Cf. A194918, A194917, A189663, A194959. %K A194919 nonn %O A194919 1,2 %A A194919 _Clark Kimberling_, Sep 08 2011