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A224723 Number of (n+3) X 6 0..2 matrices with each 4 X 4 subblock idempotent. 1
2471, 2493, 3092, 3502, 3775, 4868, 6540, 8551, 10761, 13991, 18817, 25579, 34473, 46520, 63313, 86789, 119077, 163331, 224294, 308650, 425208, 585935, 807537, 1113408, 1535747, 2118724, 2923211, 4033478, 5565990, 7681386, 10601173 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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) - 2*a(n-3) + 4*a(n-4) - 3*a(n-5) + 2*a(n-7) - a(n-8) for n>10.

Empirical g.f.: x*(2471 - 4920*x + 555*x^2 + 4154*x^3 - 5445*x^4 + 4172*x^5 + 1601*x^6 - 3457*x^7 + 815*x^8 + 52*x^9) / ((1 - x)^3*(1 + x)*(1 - x - x^4)). - Colin Barker, Sep 04 2018

EXAMPLE

Some solutions for n=2:

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

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

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

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

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

CROSSREFS

Column 3 of A224728.

Sequence in context: A253355 A204614 A204798 * A183703 A282559 A278733

Adjacent sequences:  A224720 A224721 A224722 * A224724 A224725 A224726

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 16 2013

STATUS

approved

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Last modified January 22 05:19 EST 2022. Contains 350481 sequences. (Running on oeis4.)