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 A197679 #7 Jun 02 2025 05:05:28 %S A197679 1,3,3,4,9,4,5,16,16,5,9,33,57,33,9,16,73,202,202,73,16,25,160,721, %T A197679 1111,721,160,25,39,361,2557,5639,5639,2557,361,39,64,835,8930,29190, %U A197679 45162,29190,8930,835,64,105,1966,31326,153715,358209,358209,153715,31326,1966 %N A197679 T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,0,1,0,1 for x=0,1,2,3,4. %C A197679 Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 0's, every 4 is next to 4 1's %C A197679 Table starts %C A197679 ...1....3......4........5..........9..........16............25..............39 %C A197679 ...3....9.....16.......33.........73.........160...........361.............835 %C A197679 ...4...16.....57......202........721........2557..........8930...........31326 %C A197679 ...5...33....202.....1111.......5639.......29190........153715..........817865 %C A197679 ...9...73....721.....5639......45162......358209.......2871646........22955155 %C A197679 ..16..160...2557....29190.....358209.....4268977......51167876.......612121676 %C A197679 ..25..361...8930...153715....2871646....51167876.....924904506.....16683567785 %C A197679 ..39..835..31326...817865...22955155...612121676...16683567785....452341382317 %C A197679 ..64.1966.110217..4363976..183536379..7361707007..302284521370..12312981845426 %C A197679 .105.4703.387627.23310791.1469158622.88656931195.5474405589906.335130309920001 %H A197679 R. H. Hardin, <a href="/A197679/b197679.txt">Table of n, a(n) for n = 1..180</a> %e A197679 Some solutions containing all values 0 to 4 for n=6 k=4 %e A197679 ..1..0..0..0....1..1..1..1....1..2..2..1....2..1..0..0....0..0..0..1 %e A197679 ..1..0..3..0....0..0..0..0....0..1..1..0....1..4..1..1....3..0..3..2 %e A197679 ..1..1..1..0....0..3..0..0....0..1..4..1....0..1..1..1....0..0..0..1 %e A197679 ..0..1..1..0....0..1..1..1....0..1..1..1....0..3..0..0....1..1..1..1 %e A197679 ..1..1..4..1....1..4..1..1....0..3..0..0....3..0..3..1....1..4..1..0 %e A197679 ..1..0..1..2....2..1..0..0....0..0..0..0....0..0..0..1....0..1..1..0 %Y A197679 Column 1 is A195971 %Y A197679 Column 2 is A197531 %K A197679 nonn,tabl %O A197679 1,2 %A A197679 _R. H. Hardin_ Oct 17 2011