# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a198639 Showing 1-1 of 1 %I A198639 #5 Mar 31 2012 12:36:34 %S A198639 36,2436,162776,10937316,734979136,49393306556,3319433387656, %T A198639 223079838087956,14991902921730896,1007518927448282476, %U A198639 67709509526621985176,4550363827896811116996,305803588199889010224736 %N A198639 Number of 2nX4 0..2 arrays with values 0..2 introduced in row major order and each element equal to an even number of horizontal and vertical neighbors %C A198639 Column 2 of A198642 %H A198639 R. H. Hardin, Table of n, a(n) for n = 1..200 %F A198639 Empirical: a(n) = 78*a(n-1) -569*a(n-2) -11744*a(n-3) +71840*a(n-4) +745984*a(n-5) -2507008*a(n-6) -18538496*a(n-7) +36110336*a(n-8) +142606336*a(n-9) -268435456*a(n-10) %e A198639 Some solutions for n=3 %e A198639 ..0..1..0..2....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1 %e A198639 ..1..0..1..0....1..0..1..0....1..0..2..0....1..0..1..0....1..0..2..0 %e A198639 ..2..1..2..1....2..2..0..1....2..1..0..1....2..1..0..1....2..1..0..1 %e A198639 ..1..2..1..2....2..2..1..0....0..2..1..2....1..2..1..0....1..2..1..2 %e A198639 ..2..0..2..0....0..1..2..1....2..1..2..0....0..1..0..2....2..1..0..1 %e A198639 ..1..2..0..1....1..0..1..0....0..2..1..2....1..0..2..1....1..2..1..2 %K A198639 nonn %O A198639 1,1 %A A198639 _R. H. Hardin_ Oct 27 2011 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE