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Number of n X n 0..5 matrices with each 2X2 subblock idempotent
0

%I #4 Dec 18 2015 18:18:35

%S 6,24,128,222,500,956,1876,3538,6622,12200,22274,40302,72418,129332,

%T 229780,406378,715800,1256248,2197512,3832510,6665570,11563364,

%U 20012598

%N Number of n X n 0..5 matrices with each 2X2 subblock idempotent

%C Column 5 of A224665

%F Empirical: a(n) = 6*a(n-1) -12*a(n-2) +5*a(n-3) +12*a(n-4) -12*a(n-5) -3*a(n-6) +6*a(n-7) -a(n-9) for n>10

%e Some solutions for n=3

%e ..0..0..0....1..1..4....1..0..5....1..1..3....1..0..2....1..0..2....1..0..0

%e ..0..0..0....0..0..0....1..0..1....0..0..0....1..0..1....1..0..1....1..0..1

%e ..2..1..1....0..0..0....0..0..1....5..1..1....2..0..1....4..0..1....3..0..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 14 2013