A224663 - OEIS

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

%S 7,28,162,268,596,1118,2166,4038,7488,13686,24818,44640,79796,141848,

%T 250966,442168,776152,1357850,2368298,4119186

%N Number of n X n 0..6 matrices with each 2X2 subblock idempotent

%C Column 6 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 ..1..1..2....1..1..6....1..1..4....0..0..0....0..1..0....1..1..0....1..0..3

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

%e ..2..1..1....3..1..1....6..1..1....4..1..1....0..1..0....0..0..1....2..0..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 14 2013