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A224552 Number of (n+2) X 3 0..1 matrices with each 3 X 3 subblock idempotent. 1
50, 70, 113, 172, 263, 418, 669, 1064, 1699, 2734, 4409, 7108, 11471, 18538, 29973, 48464, 78379, 126790, 205121, 331852, 536903, 868690, 1405533, 2274152, 3679603, 5953678, 9633209, 15586804, 25219919, 40806634, 66026469, 106833008, 172859371 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A224559.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3) - a(n-4) - a(n-5) + a(n-6) for n>7.

Empirical g.f.: x*(50 - 80*x + 53*x^2 - 57*x^3 - 4*x^4 + 39*x^5 - 7*x^6) / ((1 - x)^2*(1 + x^2)*(1 - x - x^2)). - Colin Barker, Aug 31 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

CROSSREFS

Cf. A224559.

Sequence in context: A102803 A224559 A272607 * A039473 A309123 A146170

Adjacent sequences:  A224549 A224550 A224551 * A224553 A224554 A224555

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 10 2013

STATUS

approved

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Last modified October 22 11:38 EDT 2021. Contains 348161 sequences. (Running on oeis4.)