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 A195664 #42 Aug 11 2015 15:47:52 %S A195664 0,1,1,2,0,0,3,2,2,2,4,3,1,0,1,5,4,3,1,2,2,6,5,4,3,0,1,0,7,6,5,4,3,0, %T A195664 1,1,8,7,6,5,4,3,3,0,0,9,8,7,6,5,4,2,3,3,3,10,9,8,7,6,5,4,2,1,0,1,11, %U A195664 10,9,8,7,6,5,4,2,1,3,3,12,11,10,9,8,7,6,5,4,2,0,1,0,13,12,11,10,9,8,7,6,5,4,2,0,2,2 %N A195664 Array read by antidiagonals: Consecutive finite permutations of nonnegative integers in reverse colexicographic order. %C A195664 Row n is the n-th finite permutation of {0,1,2,3...}. %H A195664 Tilman Piesk, <a href="/A195664/b195664.txt">Table of n, a(n) for n = 0..7259</a> %H A195664 Tilman Piesk, <a href="http://commons.wikimedia.org/wiki/File:Symmetric_group_4;_permutation_list_with_matrices.svg">Detailed table of the 24 permutations of 1...4</a> (A195663) %H A195664 Tilman Piesk, <a href="/A198380/a198380_1.txt">Table of the 40320 permutations of 1...8</a>, a supporting file of A198380 %H A195664 OEIS-Wiki, <a href="http://oeis.org/wiki/Orderings">Orderings</a> section <a href="http://oeis.org/wiki/Orderings#Reverse_colexicographic_order">rev colex</a> %F A195664 a(n) = A195663(n)-1. %e A195664 The first 24 permutations of nonnegative integers in rev colex order: %e A195664 00 --> 0 1 2 3 4 5 6 7 ... %e A195664 01 --> 1 0 2 3 ... %e A195664 02 --> 0 2 1 3 ... %e A195664 03 --> 2 0 1 3 ... %e A195664 04 --> 1 2 0 3 ... %e A195664 05 --> 2 1 0 3 ... %e A195664 06 --> 0 1 3 2 ... %e A195664 07 --> 1 0 3 2 ... %e A195664 08 --> 0 3 1 2 ... %e A195664 09 --> 3 0 1 2 ... %e A195664 10 --> 1 3 0 2 ... %e A195664 11 --> 3 1 0 2 ... %e A195664 12 --> 0 2 3 1 ... %e A195664 13 --> 2 0 3 1 ... %e A195664 14 --> 0 3 2 1 ... %e A195664 15 --> 3 0 2 1 ... %e A195664 16 --> 2 3 0 1 ... %e A195664 17 --> 3 2 0 1 ... %e A195664 18 --> 1 2 3 0 ... %e A195664 19 --> 2 1 3 0 ... %e A195664 20 --> 1 3 2 0 ... %e A195664 21 --> 3 1 2 0 ... %e A195664 22 --> 2 3 1 0 ... %e A195664 23 --> 3 2 1 0 ... %Y A195664 Cf. A195663 (same for positive integers, so all entries are bigger by 1). %K A195664 nonn,tabl %O A195664 0,4 %A A195664 _Tilman Piesk_, Sep 22 2011