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 A211105 1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having one, two or three distinct values 1

%I

%S 16,928,196480,151767424,427712112640,4397802725483392,

%T 164979998407434893440,22580741254744671390333952,

%U 11276035715844307701828163309696,20544048912459992331220711095896934784

%N 1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having one, two or three distinct values

%H R. H. Hardin, <a href="/A211105/b211105.txt">Table of n, a(n) for n = 1..11</a>

%e Some solutions for n=3

%e ..0..0..2..3....0..0..3..0....0..0..2..0....0..0..1..3....0..2..3..3

%e ..0..3..2..2....0..0..3..2....0..2..2..0....0..1..0..1....2..2..1..1

%e ..2..2..3..2....3..3..0..3....2..2..3..2....1..0..1..0....3..1..2..0

%e ..3..2..2..1....0..2..3..0....0..0..2..1....3..1..0..1....3..1..0..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Mar 31 2012

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Last modified January 27 23:41 EST 2022. Contains 350654 sequences. (Running on oeis4.)