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A224558 Number of (n+2) X 9 0..1 matrices with each 3 X 3 subblock idempotent. 1
669, 492, 620, 749, 988, 1298, 1668, 2201, 2961, 4001, 5477, 7609, 10670, 15089, 21515, 30870, 44505, 64420, 93537, 136129, 198469, 289752, 423446, 619292, 906226, 1326652, 1942715, 2845496, 4168480, 6107297, 8948658, 13112759, 19215426 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 7 of A224559.
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 5*a(n-3) - 4*a(n-4) + 3*a(n-5) - a(n-6) for n>8.
Empirical g.f.: x*(669 - 2184*x + 2666*x^2 - 2124*x^3 + 1928*x^4 - 1299*x^5 + 332*x^6 + 5*x^7) / ((1 - x)^3*(1 - x - x^3)). - Colin Barker, Sep 01 2018
EXAMPLE
Some solutions for n=3:
..1..1..1..1..0..0..0..0..0....0..0..0..0..0..1..0..0..0
..0..0..0..0..0..0..0..0..0....0..0..0..0..0..1..0..0..0
..0..0..0..0..0..0..0..0..0....0..0..0..0..0..1..0..0..1
..0..0..0..0..0..0..0..0..0....0..0..0..0..0..1..0..0..1
..0..0..1..1..1..1..1..1..1....0..0..0..0..0..1..0..0..1
CROSSREFS
Cf. A224559.
Sequence in context: A092797 A105212 A067875 * A250670 A235101 A232388
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2013
STATUS
approved

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Last modified July 15 19:27 EDT 2024. Contains 374334 sequences. (Running on oeis4.)