A224674 Number of (n+1) X 7 0..2 matrices with each 2 X 2 subblock idempotent.

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

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 A348544 A211815

Adjacent sequences: A224671 A224672 A224673 * A224675 A224676 A224677

Keyword

nonn

Author

R. H. Hardin, Apr 14 2013

Status

approved