

A268013


Number of n X 1 0..2 arrays with every repeated value in every row and column greater than or equal to the previous repeated value.


3



3, 9, 27, 78, 222, 622, 1722, 4719, 12821, 34575, 92637, 246788, 654120, 1725900, 4535172, 11872941, 30977943, 80575109, 208983471, 540606474, 1395061474, 3591893274, 9228660318, 23664610747, 60570324105, 154763821419, 394795932561
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OFFSET

1,1


COMMENTS

Column 1 of A268019.


LINKS

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


FORMULA

Empirical: a(n) = 6*a(n1)  9*a(n2)  4*a(n3) + 9*a(n4) + 6*a(n5) + a(n6).
Empirical g.f.: x*(3  9*x + 9*x^3 + 6*x^4 + x^5) / (1  2*x  x^2)^3.  Colin Barker, Feb 26 2018


EXAMPLE

Some solutions for n=8:
..1....2....2....1....2....1....0....0....2....1....2....0....2....2....2....2
..0....1....2....2....0....1....0....0....0....0....0....2....1....0....0....0
..2....1....2....0....0....2....1....1....2....1....2....0....2....2....0....2
..0....1....2....2....0....2....0....2....0....1....0....0....0....0....1....2
..0....0....0....2....2....1....0....2....2....2....2....1....0....1....0....0
..1....2....1....1....1....0....2....0....2....2....1....1....0....2....1....2
..1....1....2....2....2....2....2....2....0....0....0....2....0....2....2....2
..2....1....1....0....0....1....0....1....1....2....0....0....0....1....0....1


CROSSREFS

Cf. A268019.
Sequence in context: A139561 A152169 A241574 * A269613 A006810 A090401
Adjacent sequences: A268010 A268011 A268012 * A268014 A268015 A268016


KEYWORD

nonn


AUTHOR

R. H. Hardin, Jan 24 2016


STATUS

approved



