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A224685 Number of (n+4) X 7 0..1 matrices with each 5 X 5 subblock idempotent. 1
2662, 1494, 1636, 1896, 2136, 2354, 2862, 3701, 4814, 6134, 7579, 9522, 12249, 16025, 21050, 27502, 35816, 46815, 61511, 81188, 107258, 141592, 186820, 246722, 326234, 431740, 571497, 756452, 1001216, 1325438, 1755075, 2324413, 3078635, 4077559 (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) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) - a(n-7) + a(n-8) -a(n-9) + a(n-10) + a(n-12) - a(n-13) for n>17.

Empirical g.f.: x*(2662 - 3830*x + 1310*x^2 - 2544*x^3 + 1148*x^4 - 164*x^5 + 30*x^6 + 2753*x^7 - 1112*x^8 + 2503*x^9 - 1622*x^10 - 233*x^11 - 2720*x^12 + 1520*x^13 + 221*x^14 + 61*x^15 + 5*x^16) / ((1 - x)^3*(1 + x)*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 - x^3)). - Colin Barker, Sep 02 2018

EXAMPLE

Some solutions for n=2:

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

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

..0..0..0..0..0..0..0....0..0..0..0..0..0..0....0..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

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

CROSSREFS

Column 3 of A224690.

Sequence in context: A235733 A235514 A197108 * A167191 A002482 A187293

Adjacent sequences:  A224682 A224683 A224684 * A224686 A224687 A224688

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 15 2013

STATUS

approved

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Last modified January 27 06:18 EST 2022. Contains 350601 sequences. (Running on oeis4.)