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%I #5 Mar 31 2012 12:36:34
%S 4,52,662,8784,112750,1478756,19399132,254611868,3341562350,
%T 43867978456,575917076750,7560973295748,99265283146820,
%U 1303224636522612,17109671915393798,224628189063611744,2949082376664452782
%N Number of 2nX8 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors
%C Column 4 of A198285
%H R. H. Hardin, <a href="/A198281/b198281.txt">Table of n, a(n) for n = 1..193</a>
%F Empirical: a(n) = 20*a(n-1) -94*a(n-2) +30*a(n-3) +991*a(n-4) -14152*a(n-5) +57737*a(n-6) +47122*a(n-7) -441218*a(n-8) +2956618*a(n-9) -10811467*a(n-10) -23072476*a(n-11) +84378808*a(n-12) -161949862*a(n-13) +516000620*a(n-14) +2832666716*a(n-15) -3992016864*a(n-16) -5147127328*a(n-17) +8009660032*a(n-18) -125833211136*a(n-19) -133111885824*a(n-20) +321245103104*a(n-21) -748696293376*a(n-22) +5854699044864*a(n-23) +11597031440384*a(n-24) -9315056222208*a(n-25) +725672263680*a(n-26) -167805362634752*a(n-27) -267408019292160*a(n-28) +267698466455552*a(n-29) +891968070615040*a(n-30) +545959062798336*a(n-31) +2070380395102208*a(n-32) +1440360232386560*a(n-33) -14953358137753600*a(n-34) -4644337115725824*a(n-35) +18014398509481984*a(n-36)
%e Some solutions for n=3
%e ..0..0..1..1..0..0..2..2....0..0..0..0..1..1..0..0....0..0..1..1..0..0..1..1
%e ..0..0..1..1..0..0..2..2....0..2..2..0..1..1..0..0....0..0..1..1..0..0..1..1
%e ..2..2..2..2..2..2..0..0....0..2..2..0..2..2..2..2....1..1..0..0..2..2..2..2
%e ..2..0..0..1..1..2..0..0....0..0..0..0..2..1..1..2....1..1..0..0..2..0..0..2
%e ..2..0..0..1..1..2..1..1....2..2..1..1..2..1..1..2....0..0..1..1..2..0..0..2
%e ..2..2..2..2..2..2..1..1....2..2..1..1..2..2..2..2....0..0..1..1..2..2..2..2
%K nonn
%O 1,1
%A _R. H. Hardin_ Oct 23 2011
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