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 A085576 #4 Mar 30 2012 16:49:45 %S A085576 1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,3,3,3,3,2,3,3,4,4,4,3,3,3,4,4,5,5,4, %T A085576 4,3,3,4,5,6,6,6,5,4,3,4,5,6,6,7,7,6,6,5,4,4,5,6,8,8,8,8,8,6,5,4,4,6, %U A085576 7,8,9,9,9,9,8,7,6,4 %N A085576 Array read by antidiagonals: T(n,k) = size of maximal subset of nodes in n X k grid such that there at least 3 edges between any pair of nodes (n >= 1, k >= 1). %C A085576 The 1-neighborhoods of the nodes must be disjoint: i.e. this is a 1-error correcting code. %F A085576 T(n, 1) = floor((n+2)/3), T(n, 2) = floor((n+1)/2). %e A085576 Array begins %e A085576 1 1 1 2 2 2 3 3 3 4 ... %e A085576 1 1 2 2 3 3 4 4 5 5 ... %e A085576 1 2 2 3 4 4 5 6 6 7 ... %e A085576 2 2 3 4 5 6 6 8 8 9 ... %e A085576 For example, T(3,4) = 3 (*'s indicate the chosen nodes): %e A085576 o--*--o--o %e A085576 |..|..|..| %e A085576 o--o--o--o %e A085576 |..|..|..| %e A085576 *--o--o--* %Y A085576 Main diagonal gives A085577. %K A085576 nonn,tabl %O A085576 1,7 %A A085576 _N. J. A. Sloane_, Jul 08 2003