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A224675 Number of (n+1) X 8 0..2 matrices with each 2 X 2 subblock idempotent. 1
308, 470, 617, 864, 1166, 1608, 2230, 3157, 4554, 6711, 10083, 15415, 23907, 37504, 59351, 94538, 151300, 242962, 391084, 630551, 1017808, 1644185, 2657457, 4296729, 6948881, 11239898, 18182645, 29415972, 47591594, 77000076, 124583698 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A224676.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

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

Empirical g.f.: x*(308 - 762*x + 277*x^2 + 438*x^3 - 291*x^4 + 15*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Feb 17 2018

EXAMPLE

Some solutions for n=3:

  0 0 0 1 0 0 0 0    1 0 1 0 0 0 0 0    1 1 1 1 1 1 1 1

  0 0 0 1 0 0 0 0    1 0 1 0 0 0 0 0    0 0 0 0 0 0 0 0

  0 0 0 1 0 0 0 0    1 0 1 0 0 0 0 0    0 0 0 0 0 0 0 1

  0 0 0 1 0 0 1 1    2 0 1 0 0 0 1 1    0 0 0 0 0 0 0 1

CROSSREFS

Sequence in context: A234030 A309566 A118843 * A249552 A237457 A234211

Adjacent sequences:  A224672 A224673 A224674 * A224676 A224677 A224678

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 14 2013

STATUS

approved

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Last modified October 26 08:00 EDT 2021. Contains 348267 sequences. (Running on oeis4.)