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A185825 T(n,k)=1/5 the number of nXk 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

%I A185825 #9 Jul 22 2025 10:02:35
%S A185825 0,1,1,1,9,1,5,76,76,5,9,656,1584,656,9,29,5680,49036,49036,5680,29,
%T A185825 65,49248,1266624,4443292,1266624,49248,65,181,426928,35446376,
%U A185825 378212944,378212944,35446376,426928,181,441,3701360,956312244,32995092992
%N A185825 T(n,k)=1/5 the number of nXk 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
%C A185825 Table starts
%C A185825 ....0........1...........1.............5..............9.............29
%C A185825 ....1........9..........76...........656...........5680..........49248
%C A185825 ....1.......76........1584.........49036........1266624.......35446376
%C A185825 ....5......656.......49036.......4443292......378212944....32995092992
%C A185825 ....9.....5680.....1266624.....378212944...100480040192.28043363244452
%C A185825 ...29....49248....35446376...32995092992.28043363244452
%C A185825 ...65...426928...956312244.2852526229300
%C A185825 ..181..3701360.26231137608
%C A185825 ..441.32089696
%C A185825 .1165
%H A185825 R. H. Hardin, <a href="/A185825/b185825.txt">Table of n, a(n) for n = 1..60</a>
%e A185825 Some solutions for 5X4 with a(1,1)=0
%e A185825 ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
%e A185825 ..1..1..1..0....0..1..1..0....1..1..1..0....1..1..1..0....0..1..1..0
%e A185825 ..3..0..3..0....4..2..2..0....2..3..0..0....2..2..2..0....4..1..2..0
%e A185825 ..3..0..3..0....4..0..2..1....2..3..0..2....0..0..4..4....4..0..2..4
%e A185825 ..3..2..2..2....0..0..2..1....3..3..0..2....4..4..2..2....4..0..2..4
%Y A185825 Column 1 is A006131(n-2)
%K A185825 nonn,tabl
%O A185825 1,5
%A A185825 _R. H. Hardin_ Feb 05 2011