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 A209650 #7 Jul 22 2025 21:52:47 %S A209650 2,4,4,6,16,6,9,36,36,8,14,81,102,64,10,22,196,270,216,100,12,35,484, %T A209650 798,630,390,144,14,56,1225,2354,2156,1215,636,196,16,90,3136,7210, %U A209650 7128,4690,2079,966,256,18,145,8100,22232,24990,16830,8904,3276,1392,324,20,234 %N A209650 T(n,k)=Number of nXk 0..1 arrays avoiding 0 0 1 and 1 0 0 horizontally and 0 0 1 and 1 0 1 vertically. %C A209650 Table starts %C A209650 ..2...4....6....9....14.....22.....35......56.......90......145.......234 %C A209650 ..4..16...36...81...196....484...1225....3136.....8100....21025.....54756 %C A209650 ..6..36..102..270...798...2354...7210...22232....69570...218950....693810 %C A209650 ..8..64..216..630..2156...7128..24990...87136...311040..1112150...4018716 %C A209650 .10.100..390.1215..4690..16830..65765..251160...994050..3911375..15639390 %C A209650 .12.144..636.2079..8904..34012.145775..597856..2579940.10954895..47622744 %C A209650 .14.196..966.3276.15386..61754.287140.1247736..5805450.26247900.122620446 %C A209650 .16.256.1392.4860.24808.103664.518700.2364992.11769120.56106300.279344520 %H A209650 R. H. Hardin, <a href="/A209650/b209650.txt">Table of n, a(n) for n = 1..2828</a> %F A209650 Empirical for column k: %F A209650 k=1: a(n) = 2*n %F A209650 k=2: a(n) = 4*n^2 %F A209650 k=3: a(n) = 2*n^3 + 6*n^2 - 2*n %F A209650 k=4: a(n) = 9*n^3 + (9/2)*n^2 - (9/2)*n %F A209650 k=5: a(n) = (7/2)*n^4 + 21*n^3 - (7/2)*n^2 - 7*n %F A209650 k=6: a(n) = 22*n^4 + (88/3)*n^3 - 22*n^2 - (22/3)*n %F A209650 k=7: a(n) = 7*n^5 + 70*n^4 + (35/3)*n^3 - (105/2)*n^2 - (7/6)*n %e A209650 Some solutions for n=4 k=3 %e A209650 ..1..1..1....1..1..1....1..1..0....0..0..0....0..1..0....0..0..0....0..1..0 %e A209650 ..1..1..1....1..1..1....1..1..0....0..1..1....1..1..0....0..0..0....0..0..0 %e A209650 ..1..1..1....0..1..0....1..1..0....0..1..0....0..0..0....0..0..0....0..0..0 %e A209650 ..1..1..1....0..1..0....1..1..0....0..0..0....0..0..0....0..0..0....0..0..0 %Y A209650 Column 2 is A016742 %Y A209650 Column 3 is A086113 %Y A209650 Row 1 is A001611(n+2) %Y A209650 Row 2 is A207436 %Y A209650 Row 3 is A207747 %K A209650 nonn,tabl %O A209650 1,1 %A A209650 _R. H. Hardin_ Mar 11 2012