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A224672 Number of (n+1) X 5 0..2 matrices with each 2 X 2 subblock idempotent. 1
70, 123, 170, 260, 381, 573, 864, 1322, 2043, 3191, 5026, 7972, 12713, 20357, 32696, 52630, 84851, 136951, 221214, 357516, 578017, 934753, 1511920, 2445750, 3956671, 6401343, 10356854, 16756952, 27112473, 43868001, 70978956, 114845342 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A224676.

LINKS

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

FORMULA

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

Empirical g.f.: x*(70 - 157*x + 28*x^2 + 125*x^3 - 72*x^4 + 3*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Feb 17 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

CROSSREFS

Sequence in context: A004239 A185817 A260573 * A039542 A024748 A024756

Adjacent sequences:  A224669 A224670 A224671 * A224673 A224674 A224675

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 14 2013

STATUS

approved

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Last modified September 28 21:22 EDT 2021. Contains 347717 sequences. (Running on oeis4.)