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A224672 Number of (n+1) X 5 0..2 matrices with each 2 X 2 subblock idempotent. 1

%I

%S 70,123,170,260,381,573,864,1322,2043,3191,5026,7972,12713,20357,

%T 32696,52630,84851,136951,221214,357516,578017,934753,1511920,2445750,

%U 3956671,6401343,10356854,16756952,27112473,43868001,70978956,114845342

%N Number of (n+1) X 5 0..2 matrices with each 2 X 2 subblock idempotent.

%C Column 4 of A224676.

%H R. H. Hardin, <a href="/A224672/b224672.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: x*(70 - 157*x + 28*x^2 + 125*x^3 - 72*x^4 + 3*x^5) / ((1 - x)^3*(1 - x - x^2)). - _Colin Barker_, Feb 17 2018

%e Some solutions for n=3:

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 14 2013

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Last modified October 27 13:45 EDT 2021. Contains 348276 sequences. (Running on oeis4.)