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A224722 Number of (n+3) X 5 0..2 matrices with each 4 X 4 subblock idempotent. 1
1623, 1920, 2493, 2863, 3123, 4129, 5711, 7604, 9713, 12764, 17344, 23754, 32224, 43673, 59650, 81969, 112701, 154811, 212841, 293114, 404063, 557046, 767994, 1059140, 1461174, 2016107, 2781924, 3838807, 5297655, 7311353, 10090799 (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) - 2*a(n-5) + a(n-6) - 2*a(n-7) + 2*a(n-8) + a(n-11) - a(n-12) for n>15.

Empirical g.f.: x*(1623 - 1326*x + 276*x^2 - 1826*x^3 - 2030*x^4 + 1499*x^5 - 70*x^6 + 3500*x^7 - 86*x^8 - 240*x^9 - 200*x^10 - 1693*x^11 + 508*x^12 + 48*x^13 + 5*x^14) / ((1 - x)^3*(1 + x)*(1 + x^2)*(1 + x + x^2)*(1 - x - x^4)). - Colin Barker, Sep 03 2018

EXAMPLE

Some solutions for n=2:

  0 0 0 0 1     1 0 0 0 1     0 0 0 0 0     1 0 0 0 0

  0 0 0 0 1     1 0 0 0 1     1 1 1 1 1     1 0 0 0 0

  0 0 0 0 2     0 0 0 0 1     0 0 0 0 0     2 0 0 0 1

  0 0 0 0 1     2 0 0 0 1     0 0 0 0 0     0 0 0 0 1

  0 0 0 0 1     2 0 0 0 1     0 0 0 0 0     0 0 0 0 1

CROSSREFS

Column 2 of A224728.

Sequence in context: A269274 A020418 A347039 * A045288 A204726 A022060

Adjacent sequences:  A224719 A224720 A224721 * A224723 A224724 A224725

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 16 2013

STATUS

approved

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Last modified January 24 13:48 EST 2022. Contains 350538 sequences. (Running on oeis4.)