# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a209907 Showing 1-1 of 1 %I A209907 #5 Mar 31 2012 12:37:30 %S A209907 562,13098,295448,6711168,152153160,3452051294,78298719958, %T A209907 1776153151954,40289004709802,913904480044196,20730591242525088, %U A209907 470244787257936734,10666837893533545782,241962270764619764754,5488573721848784927246 %N A209907 Half the number of (n+1)X3 0..3 arrays with every 2X2 subblock having two or four distinct clockwise edge differences %C A209907 Column 2 of A209913 %H A209907 R. H. Hardin, Table of n, a(n) for n = 1..210 %F A209907 Empirical: a(n) = 16*a(n-1) +227*a(n-2) -1440*a(n-3) -8244*a(n-4) +46409*a(n-5) +53926*a(n-6) -406100*a(n-7) -117231*a(n-8) +1484559*a(n-9) +166049*a(n-10) -2587430*a(n-11) -386782*a(n-12) +2096907*a(n-13) +472125*a(n-14) -660956*a(n-15) -166954*a(n-16) +44616*a(n-17) +4488*a(n-18) -192*a(n-19) %e A209907 Some solutions for n=4 %e A209907 ..3..0..1....3..0..0....2..2..1....1..2..3....3..0..1....3..3..1....1..1..3 %e A209907 ..2..0..3....1..1..3....3..0..2....2..3..1....1..3..0....1..0..3....0..3..0 %e A209907 ..1..2..0....3..0..3....0..3..3....1..2..3....2..1..1....2..3..0....0..1..0 %e A209907 ..2..0..3....2..0..1....1..0..2....3..1..2....1..3..0....1..2..1....0..3..1 %e A209907 ..0..2..0....2..3..1....1..3..2....3..0..3....3..0..1....2..1..2....3..0..0 %K A209907 nonn %O A209907 1,1 %A A209907 _R. H. Hardin_ Mar 15 2012 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE