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A224549 Number of (n+1) X 8 0..1 matrices with each 2 X 2 subblock idempotent. 1
216, 345, 472, 682, 943, 1323, 1858, 2652, 3845, 5681, 8544, 13062, 20247, 31739, 50190, 79892, 127789, 205117, 330056, 532022, 858611, 1386835, 2241302, 3623632, 5860053, 9478413, 15332788, 24805102, 40131355, 64929471, 105053374, 169974912 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A224550.

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*(216 - 519*x + 172*x^2 + 303*x^3 - 202*x^4 + 15*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Aug 31 2018

EXAMPLE

Some solutions for n=3:

..1..1..1..0..0..1..0..0....1..0..0..0..0..0..0..0....1..1..1..0..0..0..0..0

..0..0..0..0..0..1..0..1....1..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0

..0..0..0..0..0..1..0..1....1..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0

..0..0..0..0..0..1..0..1....0..0..0..0..0..1..1..1....0..0..0..0..0..0..1..1

CROSSREFS

Cf. A224550.

Sequence in context: A115430 A278976 A179419 * A327284 A043371 A304369

Adjacent sequences:  A224546 A224547 A224548 * A224550 A224551 A224552

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 10 2013

STATUS

approved

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Last modified March 29 18:31 EDT 2020. Contains 333117 sequences. (Running on oeis4.)