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 A350823 #12 Feb 16 2025 08:34:02 %S A350823 1,1,1,1,2,1,2,2,2,2,2,3,3,3,2,2,3,4,4,3,2,3,4,4,4,4,4,3,3,4,5,6,6,5, %T A350823 4,3,3,5,6,7,7,7,6,5,3,4,5,7,7,8,8,7,7,5,4,4,6,7,8,9,10,9,8,7,6,4,4,6, %U A350823 8,10,11,11,11,11,10,8,6,4 %N A350823 Array read by antidiagonals: T(m,n) is the domination number of the grid graph P_m X P_n. %C A350823 Equivalently, the minimum number of X-pentominoes needed to cover an m X n grid. %H A350823 Andrew Howroyd, <a href="/A350823/b350823.txt">Table of n, a(n) for n = 1..276</a> %H A350823 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DominationNumber.html">Domination Number</a> %H A350823 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GridGraph.html">Grid Graph</a> %F A350823 T(m,n) = T(n,m). %F A350823 T(1,n) = ceiling(n/3); T(2,n) = floor(n/2) + 1. %e A350823 Table begins: %e A350823 =================================== %e A350823 m\n | 1 2 3 4 5 6 7 8 9 %e A350823 ----+------------------------------ %e A350823 1 | 1 1 1 2 2 2 3 3 3 ... %e A350823 2 | 1 2 2 3 3 4 4 5 5 ... %e A350823 3 | 1 2 3 4 4 5 6 7 7 ... %e A350823 4 | 2 3 4 4 6 7 7 8 10 ... %e A350823 5 | 2 3 4 6 7 8 9 11 12 ... %e A350823 6 | 2 4 5 7 8 10 11 12 14 ... %e A350823 7 | 3 4 6 7 9 11 12 14 16 ... %e A350823 8 | 3 5 7 8 11 12 14 16 18 ... %e A350823 9 | 3 5 7 10 12 14 16 18 20 ... %e A350823 ... %Y A350823 Row 4 is A193768. %Y A350823 Main diagonal is A104519. %Y A350823 Cf. A286847, A300358, A350820. %K A350823 nonn,tabl %O A350823 1,5 %A A350823 _Andrew Howroyd_, Jan 17 2022