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A224544 Number of (n+1) X 3 0..1 matrices with each 2 X 2 subblock idempotent. 1
16, 32, 52, 86, 137, 218, 345, 547, 869, 1385, 2214, 3549, 5702, 9178, 14794, 23872, 38551, 62292, 100695, 162821, 263331, 425947, 689052, 1114751, 1803532, 2917988, 4721200, 7638842, 12359669, 19998110, 32357349, 52354999, 84711857, 137066333 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A224550.
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + a(n-3) + 2*a(n-4) - a(n-5).
Empirical g.f.: x*(16 - 32*x + 4*x^2 + 22*x^3 - 11*x^4) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Aug 30 2018
EXAMPLE
Some solutions for n=3:
..1..1..1....0..0..0....1..1..1....1..0..0....1..0..0....1..0..0....1..0..0
..0..0..0....0..0..0....0..0..0....1..0..0....1..0..0....0..0..0....1..0..1
..0..0..0....0..0..0....0..0..1....1..0..0....1..0..0....0..0..0....1..0..1
..0..0..0....0..1..1....0..0..1....1..0..0....0..0..0....1..1..1....1..0..1
CROSSREFS
Cf. A224550.
Sequence in context: A082294 A048946 A260050 * A255994 A204645 A236323
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2013
STATUS
approved

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Last modified May 22 13:22 EDT 2024. Contains 372755 sequences. (Running on oeis4.)