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 A180428 #2 Mar 30 2012 17:23:31 %S A180428 1,2,6,3,10,16,19,22,11,4,64,25,5,20,17,9,27,35,7,31,37,41,15,52,60, %T A180428 55,33,47,57,134,75,68,71,80,65,62,78,8,82,151,85,18,14,87,21,141,89, %U A180428 13,23,28,131,94,101,193,109,106,113,116,233,122,111,145,170,24,124 %N A180428 Inverse permutation of A180427. Also the absolute values of the first differences of A180427. %F A180428 a(n) = | A180427(n+1) - A180427(n) |. %Y A180428 Cf. A180427 Inverse Permutation of this sequence. %K A180428 nonn %O A180428 1,2 %A A180428 _Andrew Weimholt_, Sep 04 2010