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 A224685 Number of (n+4) X 7 0..1 matrices with each 5 X 5 subblock idempotent. 1

%I

%S 2662,1494,1636,1896,2136,2354,2862,3701,4814,6134,7579,9522,12249,

%T 16025,21050,27502,35816,46815,61511,81188,107258,141592,186820,

%U 246722,326234,431740,571497,756452,1001216,1325438,1755075,2324413,3078635,4077559

%N Number of (n+4) X 7 0..1 matrices with each 5 X 5 subblock idempotent.

%H R. H. Hardin, <a href="/A224685/b224685.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) - a(n-7) + a(n-8) -a(n-9) + a(n-10) + a(n-12) - a(n-13) for n>17.

%F Empirical g.f.: x*(2662 - 3830*x + 1310*x^2 - 2544*x^3 + 1148*x^4 - 164*x^5 + 30*x^6 + 2753*x^7 - 1112*x^8 + 2503*x^9 - 1622*x^10 - 233*x^11 - 2720*x^12 + 1520*x^13 + 221*x^14 + 61*x^15 + 5*x^16) / ((1 - x)^3*(1 + x)*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 - x^3)). - _Colin Barker_, Sep 02 2018

%e Some solutions for n=2:

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

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

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

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

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

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

%Y Column 3 of A224690.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 15 2013

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Last modified May 19 17:07 EDT 2022. Contains 353847 sequences. (Running on oeis4.)