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 A168142 #10 Jul 24 2016 22:24:42
%S A168142 2,1,8,7,6,5,4,3,2,1,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,32,
%T A168142 31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,
%U A168142 8,7,6,5,4,3,2,1,50,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35,34,33,32,31
%N A168142 Count downwards from 2, then from 8, then from 18, then from ... 2*k^2, k>=1.
%C A168142 Janet's extended enumeration of the periodic table of the elements.
%C A168142 The table is read from the right to the left.
%D A168142 Charles Janet, La structure du Noyau de l'atome,consideree dans la Classification periodique des elements chimiques, Nov. 1927, N. 2, Beauvais, 67 pages, 3 leafleats, see page 15.
%D A168142 Charles Janet, Considerations sur la structure du noyau de l'atome, Dec 1929, N 5, Beauvais, 2+45 pp.,4 leaflets, see leaflets 2 and 3.
%t A168142 Table[Reverse@ Range[2 n^2], {n, 5}] // Flatten (* _Michael De Vlieger_, Jul 22 2016 *)
%Y A168142 Cf. A138100, A138101, A093907, A137583, A172002.
%K A168142 nonn
%O A168142 1,1
%A A168142 _Paul Curtz_, Nov 19 2009
%E A168142 Edited by _R. J. Mathar_, Feb 15 2010