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 A057556 #23 Aug 17 2023 11:06:03 %S A057556 0,0,0,0,0,1,0,1,0,1,0,0,0,0,2,0,1,1,0,2,0,1,0,1,1,1,0,2,0,0,0,0,3,0, %T A057556 1,2,0,2,1,0,3,0,1,0,2,1,1,1,1,2,0,2,0,1,2,1,0,3,0,0,0,0,4,0,1,3,0,2, %U A057556 2,0,3,1,0,4,0,1,0,3,1,1,2,1,2,1,1,3,0,2,0,2,2,1,1,2,2,0,3,0,1,3,1,0,4,0,0,0,0,5,0,1,4,0,2,3,0,3,2,0,4,1,0,5,0,1,0,4,1,1,3,1,2,2,1,3,1,1,4,0,2,0,3,2,1,2,2,2,1,2,3,0,3,0,2,3,1,1,3,2,0,4,0,1,4,1,0,5,0,0 %N A057556 Lexicographic ordering of M x M x M, where M={0,1,2,...}. %C A057556 See A057557 for N x N x N, where N={1,2,3,...}. %C A057556 The triples are sorted first according to their sum, then lexicographically. - _Pontus von Brömssen_, Aug 16 2023 %H A057556 Alois P. Heinz, <a href="/A057556/b057556.txt">Table of n, a(n) for n = 1..10962</a> %e A057556 Flatten the list of ordered lattice points, (0,0,0) < (0,0,1) < (0,1,0) < ... to 0,0,0, 0,0,1, 0,1,0, ... %e A057556 As a three-column array: %e A057556 0 0 0 %e A057556 0 0 1 %e A057556 0 1 0 %e A057556 1 0 0 %e A057556 0 0 2 %e A057556 0 1 1 %e A057556 0 2 0 %e A057556 1 0 1 %e A057556 1 1 0 %e A057556 2 0 0 %e A057556 0 0 3 %e A057556 0 1 2 %e A057556 0 2 1 %e A057556 0 3 0 %e A057556 1 0 2 %e A057556 1 1 1 %e A057556 1 2 0 %e A057556 2 0 1 %e A057556 2 1 0 %e A057556 3 0 0 %e A057556 ... %t A057556 lexicographicLattice[{dim_,maxHeight_}]:= Flatten[Array[Sort@Flatten[(Permutations[#1]&)/@IntegerPartitions[#1+dim-1,{dim}],1]&,maxHeight],1]; Flatten@lexicographicLattice[{3,6}]-1 %t A057556 (* _Peter J. C. Moses_, Feb 10 2011 *) %Y A057556 Cf. A057554, A057557. %Y A057556 Cf. A144625 (each triple reversed). %K A057556 nonn,tabf %O A057556 1,15 %A A057556 _Clark Kimberling_, Sep 07 2000 %E A057556 Extended by _Clark Kimberling_, Feb 10 2011