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 A232589 #6 Jul 23 2025 07:31:12 %S A232589 0,10,2,2,34,4,26,12,124,6,20,152,42,456,10,70,108,996,122,1686,18,90, %T A232589 690,606,6406,332,6232,32,210,744,8104,3002,41328,882,23034,56,336, %U A232589 3232,7568,93236,14398,266490,2322,85130,98,674,4516,66744,68072,1079300 %N A232589 T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with every element next to itself plus and minus one within the range 0..2 horizontally or antidiagonally, with no adjacent elements equal. %C A232589 Table starts %C A232589 ...0......10.....2........26.......20...........70..........90.............210 %C A232589 ...2......34....12.......152......108..........690.........744............3232 %C A232589 ...4.....124....42.......996......606.........8104........7568...........66744 %C A232589 ...6.....456...122......6406.....3002........93236.......68072.........1364998 %C A232589 ..10....1686...332.....41328....14398......1079300......595304........28339640 %C A232589 ..18....6232...882....266490....66950.....12486510.....5045772.......589476500 %C A232589 ..32...23034..2322...1718514...306022....144506106....41969054.....12273587770 %C A232589 ..56...85130..6092..11082034..1382638...1672314806...344123498....255585490674 %C A232589 ..98..314626.15962..71463916..6200520..19353375198..2791211292...5322596390316 %C A232589 .172.1162804.41802.460844060.27671244.223972627480.22459482618.110844512072980 %H A232589 R. H. Hardin, <a href="/A232589/b232589.txt">Table of n, a(n) for n = 1..477</a> %F A232589 Empirical for column k: %F A232589 k=1: a(n) = 2*a(n-1) -a(n-2) +a(n-3) %F A232589 k=2: a(n) = 4*a(n-1) -a(n-2) -a(n-3) +2*a(n-4) %F A232589 k=3: a(n) = 4*a(n-1) -4*a(n-2) +a(n-3) %F A232589 k=4: a(n) = 5*a(n-1) +9*a(n-2) +2*a(n-3) +a(n-4) +2*a(n-5) %F A232589 k=5: [order 14] %F A232589 k=6: [order 23] for n>27 %F A232589 k=7: [order 44] for n>45 %F A232589 Empirical for row n: %F A232589 n=1: a(n) = -a(n-1) +2*a(n-2) +4*a(n-3) +3*a(n-4) +a(n-5) %F A232589 n=2: [order 9] for n>10 %F A232589 n=3: [order 24] for n>26 %F A232589 n=4: [order 49] for n>54 %e A232589 Some solutions for n=5 k=4 %e A232589 ..2..1..2..1..0....2..1..2..1..0....2..1..0..1..2....0..1..2..1..0 %e A232589 ..0..1..2..1..0....0..1..0..1..2....2..1..0..1..2....2..1..0..1..2 %e A232589 ..2..1..2..1..2....0..1..2..1..2....0..1..2..1..0....0..1..2..1..2 %e A232589 ..0..1..2..1..0....0..1..0..1..2....2..1..0..1..2....0..1..0..1..0 %e A232589 ..2..1..2..1..2....0..1..0..1..0....0..1..0..1..0....0..1..2..1..2 %e A232589 ..0..1..0..1..0....2..1..2..1..2....2..1..2..1..0....2..1..0..1..0 %K A232589 nonn,tabl %O A232589 1,2 %A A232589 _R. H. Hardin_, Nov 26 2013