A207689 - OEIS

A207689

Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 1 1 1 vertically.

9, 81, 100, 256, 576, 1156, 2500, 5476, 11664, 24964, 53824, 115600, 248004, 532900, 1144900, 2458624, 5280804, 11343424, 24364096, 52330756, 112402404, 241429444, 518563984, 1113823876, 2392383744, 5138595856, 11037183364, 23706760900

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OFFSET

1,1

COMMENTS

Column 4 of A207693.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + a(n-2) + 3*a(n-3) + a(n-4) - a(n-5) - a(n-6) for n>8.

Empirical g.f.: x*(9 + 72*x + 10*x^2 + 48*x^3 - 32*x^4 - 48*x^5 - 10*x^6 + 17*x^7) / ((1 + x^2 - x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Jun 25 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A207693.

Sequence in context: A037414 A161147 A209220 * A209225 A208502 A175370

Adjacent sequences: A207686 A207687 A207688 * A207690 A207691 A207692

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 19 2012

STATUS

approved