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 A216612 #6 Jul 22 2025 23:33:26 %S A216612 1,1,1,1,1,1,1,1,2,2,1,2,2,5,2,2,5,15,20,15,5,2,15,41,203,67,52,5,5, %T A216612 52,716,3429,4140,1335,203,15,5,203,2847,83440,83437,115975,6097,877, %U A216612 15,15,877,83440,2711768,18171918,20880505,4213597,192713,4140,52,15,4140 %N A216612 T(n,k)=Number of horizontal, diagonal and antidiagonal neighbor colorings of the odd squares of an nXk array with new integer colors introduced in row major order. %C A216612 Table starts %C A216612 ...1......1.........1............1..............1................2 %C A216612 ...1......1.........1............2..............5...............15 %C A216612 ...1......2.........2...........15.............41..............716 %C A216612 ...2......5........20..........203...........3429............83440 %C A216612 ...2.....15........67.........4140..........83437.........18171918 %C A216612 ...5.....52......1335.......115975.......20880505.......6423127757 %C A216612 ...5....203......6097......4213597......942420901....3376465219485 %C A216612 ..15....877....192713....190899322...484968748793.2486327138729353 %C A216612 ..15...4140...1094076..10480142147.33862631596393 %C A216612 ..52..21147..49055292.682076806159 %C A216612 ..52.115975.329588907 %C A216612 .203.678570 %H A216612 R. H. Hardin, <a href="/A216612/b216612.txt">Table of n, a(n) for n = 1..96</a> %e A216612 Some solutions for n=4 k=4 %e A216612 ..x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1 %e A216612 ..2..x..3..x....2..x..3..x....1..x..2..x....2..x..3..x....1..x..2..x %e A216612 ..x..4..x..2....x..1..x..2....x..0..x..3....x..4..x..0....x..3..x..4 %e A216612 ..5..x..6..x....4..x..3..x....2..x..1..x....2..x..5..x....0..x..2..x %Y A216612 Column 2 is A000110(n-1) %Y A216612 Column 4 is A020557(n-1) %Y A216612 Column 6 is A208051 %Y A216612 Row 2 is A000110(n-2) %Y A216612 Row 4 is A216462 %Y A216612 Row 6 is A216464 %Y A216612 Even squares: A216460 %K A216612 nonn,tabl %O A216612 1,9 %A A216612 _R. H. Hardin_ Sep 10 2012