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A224558 Number of (n+2) X 9 0..1 matrices with each 3 X 3 subblock idempotent. 1

%I

%S 669,492,620,749,988,1298,1668,2201,2961,4001,5477,7609,10670,15089,

%T 21515,30870,44505,64420,93537,136129,198469,289752,423446,619292,

%U 906226,1326652,1942715,2845496,4168480,6107297,8948658,13112759,19215426

%N Number of (n+2) X 9 0..1 matrices with each 3 X 3 subblock idempotent.

%C Column 7 of A224559.

%H R. H. Hardin, <a href="/A224558/b224558.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 5*a(n-3) - 4*a(n-4) + 3*a(n-5) - a(n-6) for n>8.

%F Empirical g.f.: x*(669 - 2184*x + 2666*x^2 - 2124*x^3 + 1928*x^4 - 1299*x^5 + 332*x^6 + 5*x^7) / ((1 - x)^3*(1 - x - x^3)). - _Colin Barker_, Sep 01 2018

%e Some solutions for n=3:

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

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

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

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

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

%Y Cf. A224559.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 10 2013

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Last modified January 29 03:07 EST 2022. Contains 350672 sequences. (Running on oeis4.)