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A224553 Number of (n+2) X 4 0..1 matrices with each 3 X 3 subblock idempotent. 1
70, 94, 133, 174, 246, 351, 492, 693, 992, 1418, 2036, 2937, 4253, 6169, 8973, 13073, 19074, 27857, 40723, 59566, 87173, 127620, 186889, 273737, 401009, 587520, 860854, 1261428, 1848486, 2708844, 3969747, 5817672, 8525924, 12495041, 18312050 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A224559.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) - a(n-3) + a(n-4) - a(n-5) + 2*a(n-6) - a(n-7) for n>9.

Empirical g.f.: x*(70 - 116*x - 9*x^2 + 33*x^3 + 14*x^4 + 70*x^5 - 74*x^6 + 6*x^7 + 4*x^8) / ((1 - x)^3*(1 + x)*(1 - x - x^3)). - Colin Barker, Aug 31 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

CROSSREFS

Cf. A224559.

Sequence in context: A165632 A295807 A136117 * A156718 A007621 A051971

Adjacent sequences:  A224550 A224551 A224552 * A224554 A224555 A224556

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 10 2013

STATUS

approved

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Last modified October 16 19:27 EDT 2021. Contains 348044 sequences. (Running on oeis4.)