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A224674 Number of (n+1) X 7 0..2 matrices with each 2 X 2 subblock idempotent. 1
189, 300, 398, 573, 793, 1126, 1608, 2343, 3471, 5236, 8022, 12457, 19553, 30950, 49300, 78895, 126679, 203888, 328702, 530537, 856989, 1385070, 2239388, 3621563, 5857823, 9476016, 15330218, 24802353, 40128421, 64926346, 105050052, 169971387 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 6 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*(189 - 456*x + 143*x^2 + 292*x^3 - 187*x^4 + 10*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Feb 17 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

CROSSREFS

Sequence in context: A031901 A348160 A320709 * A076759 A211815 A347390

Adjacent sequences:  A224671 A224672 A224673 * A224675 A224676 A224677

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 14 2013

STATUS

approved

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Last modified October 16 19:46 EDT 2021. Contains 348044 sequences. (Running on oeis4.)