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 A131390 #2 Mar 30 2012 18:57:10 %S A131390 1,2,4,3,8,5,10,7,16,6,9,11,24,13,28,15,32,17,12,19,21,14,44,23,46,25, %T A131390 27,18,56,29,20,31,22,33,68,35,72,37,39,26,90,41,88,43,92,30,45,47,94, %U A131390 49,51,34,108,53,36,55,59,38,57,40,61,63,42,81,65,83,67,79,69,77,71,48 %N A131390 Conjectured permutation of the positive integers; inverse of conjectured permutation A131388. %F A131390 Inverse of A131388. %Y A131390 Cf. A131388, A131389, A131391, A131392, A131393, A131394, A131395, A131396, A131397. %K A131390 nonn %O A131390 1,2 %A A131390 _Clark Kimberling_, Jul 05 2007