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A224724 Number of (n+3) X 7 0..2 matrices with each 4 X 4 subblock idempotent. 1
3506, 2863, 3502, 3924, 4209, 5371, 7132, 9238, 11551, 14945, 20018, 27116, 36445, 49083, 66708, 91346, 125227, 171657, 235622, 324136, 446441, 615083, 847596, 1168530, 1611675, 2223365, 3067470, 4232412, 5840401, 8059979, 11123560 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..194

FORMULA

Empirical: a(n) = 4*a(n-1) - 7*a(n-2) + 8*a(n-3) - 6*a(n-4) + a(n-5) + 3*a(n-6) - 4*a(n-7) + 3*a(n-8) - a(n-9) for n>11.

Empirical g.f.: x*(3506 - 11161*x + 16592*x^2 - 18091*x^3 + 11159*x^4 + 1659*x^5 - 8650*x^6 + 10112*x^7 - 6687*x^8 + 1521*x^9 + 38*x^10) / ((1 - x)^3*(1 + x^2)*(1 - x - x^4)). - Colin Barker, Sep 04 2018

EXAMPLE

Some solutions for n=2:

..1..0..0..0..0..0..2....1..0..0..0..0..0..0....1..0..0..0..0..0..1

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

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

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

..2..0..0..0..0..0..1....0..0..2..1..1..1..1....0..0..0..0..0..0..1

CROSSREFS

Column 4 of A224728.

Sequence in context: A233992 A203845 A257316 * A338978 A274237 A053804

Adjacent sequences:  A224721 A224722 A224723 * A224725 A224726 A224727

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 16 2013

STATUS

approved

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Last modified October 21 04:00 EDT 2021. Contains 348141 sequences. (Running on oeis4.)